When a female has a flat ass that looks like it is just part of her legs. Because the ass looks like part of the legs the ass looks like it goes all the way down to the ankles. An ass to ankles ass can be big or small. Not to be confused with negative ass.
"Hey man, whats with her ass, it's all flat." "Yeah, she has ass to ankles"
by Copernicus P. Einstein March 11, 2009