smash the back 

A mans sexual actions on a woman, when he enters her vaginally or anally from behind in an over-excitable way.
The expression could be used best contextually in a shopping mall when your mates are cruisin' and he wants to describe ones finding of a bird across the way, he would like to "smash the back" out of, for the enjoyment of the conversation.

Oy brah... check out 3 o'clock, in line at Subway.. damnnnnn id be wise to smash the back out of that one .

smash the back by Ham6 June 12, 2018

back on the smash 

Pretty sure this was a Three 6 Mafia joint from back in the day. I'd like it to mean "back in the game" or "got it on smash", but I could be wrong.

We back on the smash!/we don't bang we blast!
'Cause we're back on the smash.

back on the smash by Halien April 9, 2008

Smash the backdoor down 

A derogatory term for forcefully penetrating a woman anus with your erect member, ferociously and with conviction, then proceed to hammer away before ejaculating.

I'm gonna smash the backdoor down of that girl when I get her home.

Smash the backdoor down by weirdalwankovich August 28, 2009