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!"
by deluks November 30, 2005
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.
by Phatty Mcgatty March 28, 2004
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
by Anonymous March 10, 2003
when a guy sees a female that he finds attractive and most likely with a ghetto booty....he will call to her by saying this
hey you....dont do me like that back dat ass up
by *~Desiree~* July 20, 2004