1: You start yelling spells at your friends, trying to tickle them with rictusempra and when you're annoyed at them, try to send snakes at them [serpensortia]
2: You know what rictusempra and serpensortia mean
3: You look up the latin meanings of the book characters
4: You bought that new Harry Potter quiz book and you know all the answers and end up getting bored
5: You own a Harry Potter website
6: You've watched the first movie so many times, you can replay the movie in your head/predict the lines perfectly
7: You own every single book of Harry Potter there is on the market, and you own the Harry Potter video game - about two copies maybe for each gaming device
8: You refer to your least favourite teacher as Snape.
9: You transfer your school subjects to the Harry Potter Versions (eg: Science -->potions, English --> study of ancient runes)(cough)
10: You quote the movie by mistake
11: The only sites you visit on the 'net are e-mail and the latest cool Harry Potter info sites and activity sites.
12: You pick up sticks from the ground, and use them for wands
13: You start to get Harry Potter costumes, and you frequently put on your wizards hat
14: You've lost count of how much Harry Potter merchandise you have bought with your weekly pocket money
15: Your bedroom walls are mostly covered with Harry Potter Posters...(cough)
16: You start drinking coca cola when you hate it, just because Coke's sponsering the movie
17: You make up your own wand cores (cough)
18: You draw Harry Potter characters on your school books
19: You make your own circular glasses - Harry Style
20: Your favourite comeback is "twitchy little ferret, aren't you?"