Back that up 

Expression used to show thanks or appreciation for something someone has done for you or it can be used after a business transaction has taken place.

Person doing favor: I got that green you wanted.

Person receiving favor: Back that up dawg.

Back that up by RAD-DADE February 23, 2009

wanna back that up with a fist 

sumthing u say to a douche who is talkin shit and cant back it up, a.k.a 7-2

gay wanna back that up with a fist ill stab u wench ahhh im sorry

wanna back that up with a fist by Anonymous May 22, 2003

Back that butt up 

an attractive luscious female ass

"woohoo hey baby back that butt up!"

Back that butt up by theCARS7879 July 13, 2018

back that ass up 

when a girl puts that delightful arch in her back, and sticks her ass out in a erotic/sexually suggestive manor, often accompanied by a "booty dance", that brings shear delight to the males species.

"did you see her back that ass up, playboy? it almost brought a tear to me eye, and a 2x4 to my pants!"

"did you see lucy liu bending over in the drive-thru scene in charlies angels?? ddaaaaaaaaamn, it was delightful! that the essence of female perfection!"

back that ass up by deluks December 28, 2005

back that ass up 

1. Back the fuck up. Get out of my face. Calm Down
2. Insist a female shake and rub her ass against you when dancing.

1. Damn nigga, back that ass up before I get crazy up in here.
2. Come here girl and back that ass up for me.

back that ass up by Phatty Mcgatty March 28, 2004

Back that ass up 

Get away BRING IT ON...

"nigguh you bettah back that ass up, BFore i bust a cap in yo ass"

Back that ass up by cornbread August 7, 2003

Back that ass up 

Song that you sing to guys with big tank asses that pass your lunch table

Whoo Whoo, sweet ass Bojangles, you's a fine mothafucka won't you back that ass up

Back that ass up by Anonymous March 10, 2003