Most girls love to be teased. Here are some quick tips:
* Take something from her and play "keep away".
* Do an impression of her.
* Throw stuff at her when she's not looking, then call her "lineman hands" or say "aww dude! you suck!"
* If she makes the slightest sexual innuendo, call her on it and accuse her with being obsessed with sex.
* If she says something dumb, "revoke her talking privileges".
* If she complains about something say "why don't you go home and cry about it" (big smile on your face).
* Tell her you gave her a nickname, but never tell her what it is.
Just be playful, smile, and have fun.