Hehe - I love these threads!
Here's my effort:
You know you're a nerd when...
... the first time you heard Rachel Stevens' song "Sweet dreams my LA ex" you thought she was singing about Los Angeles airport.
... you make an effort to do sexy helicopter landings in Battlefield Vietnam.
... you see a font in an advert and know it's name!
... you're walking down the street and see people's names floating above their heads.
... you do a superb Yoda impression with the correct grammar.
... you never get in touch with your family unless they have email.