חפשו מילה כלשהי, כמו sex:
 
1.
A woman with a very flat chest, such that it resembles her back. Only the nipples give it away.
The girl at the party was pretty, pity about her two backs.
מאת DesDDD 24 בספטמבר, 2007
 
2.
A "twoback" is a woman with no visibly protruding breasts. See also: "flat as a board."
Lucy the twoback rarely goes on second dates.

"Is that a stop sign or a twoback?"
מאת snowshoesny 26 בספטמבר, 2009