Dualy ass 

A dualy truck is really wide in the back therefore a dualy ass is one large gluteus maxiumus on any person of any race particularly women

Wow that bitch has got a major dualy ass

Dualy ass by Kizzzyle December 3, 2005

Dual moutain ass 

Coined in Whistler /Blackcomb for local women who have developed athletic but large booty due to vigorous hill climbing .

"Hey Kevin did you see at Shania, she has been in Switzerland so long she got dual moutain ass.

Dual moutain ass by dubeswiggins April 21, 2018