Often said by a man to a woman at the end of a date, because he is too much of a coward to just honestly tell her that it is not going to work out, and that he does not want to call her.
After so she feels happy and will wait for his call
B4 so he can have sex
Grey:I'll call you
*Beth waits by phone all day*
Grey: If we have sex tonight i'll call you the next day
*Next day no call*