get back to me,

or
call me back latr
hit me up

This term can be used as an goodbye greeting or when ending a conversation or at the end of trying to prove a point.

after a farewells been made you say this to the other person

is a request for affirmation

to reply to reply at your convience. To let someone know you got their message. To meet up with a lady.

it's slang, y'know "holla." Actually it's much less complicated then everyone is making it out to be. It can be traced way back to Marvin Gaye: Inner City Blues (Make me wanna holla)...think about it.