What do you say when someone calls you a girl?

If you're a girl...

"That's because I am, smart one".

or

"That's because I am one, einstein".

If you're a guy...

"Says the female"

*sniff the air* "I smell a hipocrite!" Then point accordingly to the person.

Never, ever, agree with the person. Some people say it confuses them, but honestly you are just proving their point and saying you are one, and that gives them a chance to pick on you some more plus tell other people you admited to being a girl.