Disclaimer: I do not own Harry Potter or the characters. This is for fun not profit.
Ways to annoy Snape:
Call him Snivelus
Say, "Lily never liked you"
Say, "Oh Please! Wash your hair!"
Say, "Please take a shower"
Say, "Lily doesn't like squibs like you."
Give him a bath
Fall in love with him
Remind him that Lily is dead thanks to him
Tell him that James is your best friend
Live through all of this