No tits

This expression can be used as another meaning for "You won't do it" or "You won't". It overall means, you have 'no tits so you won't do it.'. "Hey, I'm going to message him!""No tits, you won't". It is the women equivalent of no balls.
The ultimate dare from which a woman cannot back down without incurring more loss of dignity than following through with the actual stupidity of doing the dare and suffering its consequences.

A: "Hey, I'm going to message him!"
B: "No tits, you won't"