Originating from a small town in california known as cupertino... "post me" is a better, faster way to say
'keep in touch'
'keep me posted'
'get in touch with me'
'call me back,' etc.
A: "Alright, i'll see you later"
B: "forsure. post me."
A: "Hey bro, I gotta head out, but post me."
B: "sure thing. you too man"