What's your soshe? (Social security number)
Similarly:What's your soshe? (Social security number)
Here's my personal favorite, all the girls love to hear this one.
It's all in your head / mind.
I'm not being a __________(fill in the blank) it's all in your head. Oh really is it now???? Well in that case I'm not being a _________ either, you're just imagining it. Whatever.
I especially love when you say that something makes you feel (insert emotion here) and the response you get is "No, it doesn't". Seriously????