When I was a member of Restricted Section.org, I helped compile and write over 160 funny rules for Hogwarts. I contributed many of the rules in the list that follows, but the first original 50 are not mine.
Enjoy:
233. I will not poke Hufflepuffs with spoons, nor will I insist that their House colors indicate that they are "covered in bees".
234. No matter how good a fake Australian accent I can do, I will not imitate Steve Irwin during Care of Magical Creatures class.
235. Growing marijuana or hallucinogenic mushrooms is not "an extra credit project for Herbology".
236. "I've heard every possible joke about Oliver Wood's name" is not a challenge.
237. I am not allowed to attempt to breed a liger.
238. I will not go to class skyclad.
239. The Giant Squid is not an appropriate date to the Yule Ball.
240. I will not use Umbridge's quill to write "I told you I was hardcore".
241. I will stop referring to showering as "giving Moaning Myrtle an eyeful".
242. Polishing my wand in the common room is acceptable. "Polishing my wand" in the common room is not.
243. If a classmate falls asleep, I will not take advantage of that fact and draw a Dark Mark on their arm.
244. House elves are not acceptable replacements for Bludgers.
245. Starting a betting pool on the fate of this year's Defense Against the Dark Arts teacher is tasteless and tacky, not a clever money-making concept.
246. I will not start every Potions class by asking Professor Snape if today's project is suitable for use as a sexual lubricant.
247. Adding the name "Bueller" to Professor Binns' roster is not funny.
248. "Springtime for Voldemort" is not an acceptable suggestion for the class play.
249. Seamus Finnegan is not "after me Lucky Charms".
250. I will not refer to the Weasley twins as "bookends".
251. I will not refer to the Patil twins as "bookends".
252. The Slytherin prefect is named Draco Malfoy, not "Rocky Horror."
253. It is exceptionally tasteless to tell Professor Lupin that "Once you go Black, you never go back."
254. I will not call Lucius Malfoy "Jareth".
255. I will not bring a Magic Eight Ball to Divination class.
256. I am not to refer to the Potions classroom as "Kitchen Stadium".
257. I will not tell Ron and Hermione to "Get a room" whenever they start to fight.
258. The Forbidden Forest is forbidden for a reason.
259. I am not a tribble Animagus.
260. I am allowed to have a toad, rat, cat, or owl. I am not allowed to have a reticulated python, snow leopard, Tasmanian devil, or piranha.
261. I do not weigh the same as a duck.
262. Remus Lupin does not want a flea collar.
263. Sirius Black is not #24601.
264. I will not lick Trevor.
265. I will stop asking the Arithmancy teacher what the square root of -1 is.
266. I am not being repressed.
267. Calling Lucius Malfoy "Luscious Mouthful" is just plain gross.
268. I will not change the password to the prefects' bath to "Makes getting clean almost as much fun as getting dirty".
269. There is no such thing as an Invisibility Thong.
270. I am not a Pinball Wizard.
271. Asking "How do you keep a Gryffindor in suspense?" and walking away is only funny the first time.
272. I will not offer to pose nude for Colin Creevey.
273. I will not offer to pose nude for Dean Thomas.
274. It is a bad idea to tell Professor Snape he takes himself too seriously.
275. It is a bad idea to tell Professor McGonagall she takes herself too seriously.
276. Sir Cadogan is not one of the knights who say "NI".
277. I will not offer to prepare tandoori owl.
278. I will stop asking when we will learn to make "Love Potion Number Nine".
279. I will not ask Dumbledore to show me the pointy hat trick.
280. I will not greet Professor McGonagall with "What's new, pussycat?"
281. There is not now, nor has there ever been, a fifth House at Hogwarts, and I am not a member of that house, nor am I its founder.
282. I will not take out a life insurance policy on Harry Potter.
283. I will not stand in front of the bathroom door proclaiming: "None shall pass."
284. I will not refer to the house elves as 'Jar-Jar.'
285. Adding the suffix 'amus' does not create a spell. I will not test this theory of spell invention with words like 'wedgie' or 'naked.'
286. Rincewind would NOT make an acceptable DADA professor. His propensity toward survival nonwithstanding, running away does not appear in the NEWTs.
287. I will not mention rule number 34 to a Slytherin.
288. I will stop charming Professor Snape's robes to bright purple (or any bright color for that matter).
289. I will not enchant all of the school stationery so that it spells "Snogwarts School of Sexcraft and Floggery".
290. I will not send shampoo to Snape's office, no matter how badly he needs it.
291. Asking Filch if Umbridge was good in bed is a VERY bad idea.
292. I will not take Hedwig as my date to the Yule Ball.
293. Naughty jokes regarding "Moaning" Myrtle are only funny the first time.
294. Singing "Slytherins are Sexier" in Potion's class will not get me extra points.
295. Giving Luna Lovegood manga is just begging for trouble. Especially Naruto.
296. I will not send steamy singing valentines to Snape, no matter how much I'd like to see him have an aneurysm.
297. I will not mock the Snape fangirls.
298. I will not, repeat, NOT hit on Ginny Weasley. In fact, I vow to make her life miserable.
299. I will, repeat, WILL hit on Moaning Myrtle-Just to see her reaction.
300. I will not break out into show tunes in History of Magic.
301. Snape is not the Wicked Witch of the West. Nor can he be melted by water.
302. Even though they are easier to use and more effective, I will not use guns against the Deatheaters.
303. Shooting spitballs at the back of Ron Weasley's head is not acceptable behavior. No matter how fun it might be.
304. I will not scrawl "Kilroy was Here!" on the bathroom wall.
305. Screaming "VOLDEMORT!" in crowded hallways is not in good taste.
306. I will not use paint-ball guns in DADA class.
307. Stealing Draco's underwear and selling it on Ebay to horny fangirls is not ethical, nor profitable (note to self: Steal Potter's underwear instead).
308. A Bellatrix Lestrange blow-up doll is not an acceptable birthday present.
309. I will not refer to Ron Weasley as "that red-headed twit" in polite company (impolite company is just fine).
310. Star Trek references will just fly over everyone's head anyway.
311. Asking Hermione if she's bushy "everywhere" is a one-way ticket to the medical wing.
312. Arranging for Tonks to show up naked in Harry Potter's bed is not an appropriate Christmas present.
313. I will not call myself "The Dread Pirate Roberts" in class.
314. Hula hoops are not allowed in the Great Hall.
315. "East side is the best side, yo!" is not the correct answer to any question.
316. I will not put "happy pills" in the Slytherin's pumpkin juice.
317. I will not set Professor Umbridge's cardigan on fire. I will not set Professor Umbridge's cardigan on fire. I will not set Professor Umbridge's cardigan on fire...
318. If I fail to follow rule 317, I will not try to put Professor Umbridge out by blasting her into the lake.
319. I will not make "Are you Sirius?" jokes.
320. I will not pimp Harry Potter.
321. The "I Hate Snape" Club is not a valid after-class activity.
322. When I play Quidditch, I will not tie a sign saying "Eat at Joe's" to the end of my broom.
323. Making Harry Potter action figures without his permission is wrong. Making Draco Malfoy pay double for them is also wrong.
324. "Weasley is our King" is not a catchy as I think it is.
325. I will not tell Grawp that "Hermy" will give him a kiss if he eats certain members of the faculty.
326. Mail order dinosaurs are NOT good birthday presents for Hagrid. No matter how much of a discount Ingen gives you on them.
327. I will not give Dobby Pop Tarts. Ever again.
328. "Expecto Boomstick, bitches!" is not a real spell.
329. "Potter 6, Voldemort 0", is not a valid T-shirt slogan.
330. "I Cook With Snape" is also not a valid T-shirt slogan.
331. Mary Sues are not for target practice.
332. Writing sexy love letters to Professor Dumbledore, signed by "Your Kitten", is not a ethical means to skip Transfiguration class (though it is effective).
333. "Quidditch Players Do It in the Air" broom stickers are not allowed.
334. An F/A-22 Raptor jet fighter is NOT allowed in Quidditch matches. And no, you can't stick straw to it's tail and call it a broom.
335. Severus Snape is not a "sexy bitch".
336. I will not goose step in Professor Umbridge's class.
337. I will not address the Professor with a loud "Heil Fudge!" and accompanying salute.
338. I will not yell "Invasion of the Snake People!" when the Slytherins come down to breakfast.
339. Sending Remus Lupin a naked Hermione Granger and whipped cream is not an acceptable birthday gift.
340. Ron Weasley is not a crash dummy.
341. Having Colin and Dennis Creevy follow Harry Potter all day is cruel and unusual punishment.
342. Having Professor Trelawny follow Snape all day is just deserts.
343. Pansy Parkinson does not have antlers.
344. I will not light candles near Professor Snape's head.
345. Cauldrons are not to be used as musical instruments.
346. I will not sell pennies as priceless, Muggle collector coins.
347. Tollbooths are not allowed in the hallways.
348. Flobberworms are not toys.
349. Madam Hooch is not the Hawk Queen of the Skies (though she appreciates the sentiment).
350. I will not blame flying monkeys for trashing Snape's office.
351. Wedgies are just as looked down upon in the wizarding world as they are in the Muggle world.
352. Floss is not "Muggle silk".
353. I will not paint "All Hail Ferret Man!" on the Slytherin table.
354. Porn is not an acceptable submission to Gryffindor Movie Night.
355. Sombreros are not allowed at Quidditch matches.
356. Shaving Mrs. Norris is not a public service.
357. I will not filch Filch.
358. I will not sneak black dogs into Professor Trelawney's classroom.
359. I will not spread rumors about Draco's deviant sexuality.
360. Sock puppets are not allowed in class.
361. "Playwizard" is not a real magazine.
362. Snape is not "Captain Underpants".