I've given this up for adoption to another writer. I'll make a new post with details later. :)
(Ones already used, or currently in use, will be italicized and bold.)
Hermione's Diabolical List to Annoy Severus Snape
01·Every time Snape says a fact raise your hand and repeat it in the form of a question.
02·Bring candy to class and eat it, when he tells you to put it away try to bribe him to let you keep eating it with the same candy he told you to put away.
03·Follow him around during your free time, when he asks you to stop following him tell him you just happen to be going where he is.
04·Intentionally make the wrong potion during class, preferably one that either explodes, stinks, or turns the hair of everyone in the room pink
05·Ask him if he is going to cheer on the Gryffindor quidditch team every day until Gryffindor plays Slytherin.
06·Start a rumor that Professor Snape likes Professor Trelawny, make sure Trelawny hears.
07·For a whole day when you're around Professor Snape talk in rhymes.
08·Dress up like Snape, act like him, and talk like him for a day.
09·Everytime Snape looks at you blow him a kiss and wink.
10·Storm out in the middle of potions class muttering about Nargles and Crumple-Horned Snorkacks.
11·Get detention with Snape then show up late. When he yells at you tell him you were POSITIVE he said it was half a hour later than what it really was.
12·Go to his room in the middle of the night, knock, tell him you had nightmares and need someone to read you a bedtime story. When he refuses ask him to be your teddy bear instead.
13·Insist to Professor Snape that you think he would look dashing in Gold and Red.
14·Ask Snape to go with you to the Halloween Ball as Wendy and Peter Pan.
15·Smack on bubblegum in class until he notices, when he glares or tells you to throw it away look him in the eye and blow a bubble.
16·Try to give Snape a hug after every class
17·Scream in the middle of class, tell him you saw a spider on Ron's shoulder.
18·Make an unofficial opposite day, let everyone but the teachers in on it
19·Charm Snape's quill to only write nice things on student's papers when he grades them
20·Everytime Snape walks play the "Jaws" theme song.