These are some things I collected from several places, actually I made up alot of them, but some I just collected them, hope you like them and add to them if you can think of something creative!
80 Things I'm not allowed to do in Hogwarts
1- I am not allowed to send proffesor Snape a hair shampoo. No matter how he desperately needs it.
2- Asking Hermione Granger out is not a good idea.
3- Running in the corridors shouting "VOLDEMORT'S COMING" grows boring after the first three times.
4- Seamus Finnigan is not "After me lucky charms".
5- I must not put out a life insurance on Harry Potter.
6- I will not sing "We're off to see the wizard" whenever I'm sent to the headmaster's office.
7- I will not tell Professor snape that "He's taking himself too seroiusly".
8- I will not write love letters to Dumbledore signed by "Your kitten".
9- I will not write on Firenze's back "Pony rides, Three sickles per ride".
10- I must not convince first years that the new password to the Gryffindor common room is "Pertificus Totalus" and must be said with their wands pointed at themselves.
11- I must not pay first years to pee in mad-eye Moody's hip flask.
12- I must not point at the Dark Mark in the sky and shout "To the batmobile, Robin"
13- I will not lock Gryffindors and Slytherins in a room and take bets on whom will come out alive.
14- Taking bets on Harry Potter and Voldemort's next battle is never a good idea.
15- Shouting at Voldemort "The man who let the boy live" is dangerous.
16- Asking Voldemort "Why can't the Dark Mark be something more socially acceptable" might get you in trouble.
17- Asking Professor Snape about "What shampoo does he use" might end you in detention.
18- Wearing a Golden cloak and pretending to be Gilderoy Lockhart is not a good idea. You can't get rid of fan girls.
19- Although they went to Grammar school together, Dobby is not Yoda in disguise.
20- Asking Dumbledore about "The pointed hat trick" is not a good idea.
21- Starting a betting pool on this year's DADA teacher is tasteless and tacky, not the perfect way for making money.
22- "Swish and Flick" is only a wand movement.
23- Challenging Ginny Weasley for a wizard duel while you are afraid of Bats is not a good idea.
24- Crashing a Ford Angelia in the womping willow is not the perfect way to make a grand entrance. Crashing it into Snape's office is.
25- I will not wear a turban over my head and tell Harry Potter that the dark lord is back.
26- I will not, under any circumstances, or in any occasion, convince Voldemort to go on the mugglenet Chat Room.
27- I will not cook vegetables in my cauldron, especially in potions lessons.
28- "Potter 6 - Voldemort 0" is not a valid T-shirt slogan.
29- I will not give Hagrid Pokemon cards and convince him that they're real animals and that he must go look for them in the forbidden forest.
30- Stealing the Gryffindor sword from Dumbledore's office and using it to threat first years is not very good.
31- 42 is not the answer to every question in the O.W.Ls.
32- The Bloody Baron is not the perfect date for the yule ball. And yes, Even if you're The Gray Lady.
33- Messing around with Walden Macnair while on an official mission might lead you to Sir Nicholas' Fate.
34- I will not pay First years Leprechaun gold to do my dirty job. They'll notice it after a while.
35- I will not remind Voldemort every time I see him that it's not Halloween.
36- I will not ask Professor Snape why he chose Hogwarts in stead of Hollywood.
37- The Dead Man's Chest cannot be found by looking at the mirror of Erised.
38- I will not ask the Arithmancy teacher what the square root of -1 is.
49- I will not give out cookies to those who do the "Accio" Charm good.
50- I will not claim that my "X-Files" Tape is "Auror Training Videos".
51- I will not ask the Room Of Requierment to turn into "Voldemort's Hideout". "Snape's Bathroom" is a better idea.
52- I will not point out to the House Elves how much Sushi could be made of the Giant Squid.
53- I will not convince first years that Santa will not visit them in Hogwarts because they had been put under Snape's "Anti-Santa" Curse.
54- I will not get Hermione to stand infront of the mirror of Erised while in Ron's presence. That would be awkward.
55- I will not tell Professor Trelawny to "Get a life".
56- I will not come to Moaning Myrtle while she's asleep and draw on her head "50" and on her stomach "20" and on her legs "30" for each.
57- I will not use Tom Riddle's diary to throw at her.
58- I will NEVER put Fred, George, Peeves and The Marauders in one room.
59- I will not tell Sirius Black that Tonks is in love with him.
60- I will not ask Professor Flitwick if his one of the Smurfs.
61- I will not ask Dumbledore how old he really is.
62- I will not use Polyjuice potion to impersonate Voldemort and threaten first years. For one reason, Voldemort is hairless.
63- I will not charm the sorting hat to sing "If you're happy and you know it" at the start of the year feast.
64- I will not convince first years that Dumbledore is really Santa in disguise.
65- Nor will I convince them that Borgin and Burkes is a fun fair and Knockturn alley is the magical Disney Land.
66- I will not advice Draco Malfoy to go to Weasley's Wizard Wheezes. That applies to all Death Eaters as well.
67- I am not allowed to tell Mrs. Weasley that Fred and George nicked the Marauders' map from FIich's office. I might end with a Black eye.
68- Growing Marijuana or hallucinogenic mushrooms is not "an extra credit project for Herbology".
69- I am not allowed to persueade First Years into making a Treehouse over the Whomping Willow.
70- I will not ask Professor Snape about Batman's cape.
71- The Phrase "Good Dragon, Nice Dragon, Please don't kill me" Doesn't work anymore.
72- I will not attempt to use the Whomping Willow to perform a Tarazan swing.
73- I must not convince First years that painting Professor Snape's dungeon in Pink and Lavender and decorating it in Roses will get them extra points
.
74- I must not bring balls of wool and give them to Professor Mcgonagall as a birthday present.
75- I will not tune Trelawny's crystal ball to CNN.
76- I will not convince Dobby that Harry Potter's greatest desire is to own a Pit Bull Named Riper.
77- I will not intoruce first years to Fluffy.
78- I am not allowed to draw a scar on Ron Weasley's forehead. Using Avada Kedavra in him to do it is just fine.
79- I am not allowed to tell people that Voldemort is a kind, loving person compared to me, it's a one way ticket to Azkaban or to St. Mungo's Mental Health Ward.
80- And Finally, Under any condition, In any occasion or in any circumstances am I allowed to ever, ever Try to be funny while in Hogwarts.
Hope you liked them and please add some of your own!