reverse cleavage 

When the bottom of a woman's breasts show underneath a small top.

That top's so short, that girl is showing lots of reverse cleavage.

reverse cleavage by the cam September 21, 2005

Reverse Ass Cleavage 

Commonly expressed as the acronym: RAC

1) The visible outline of a girl's ass created when she wearing

leggings with either a long shirt or short dress/skirt that showcases the bottoms of her cheeks where they meet the back of her thighs. Resulting in upside-down cleavage of the ass best appreciated when she's walking up stairs.

2) Summertime variation would include the same get up sans leggings and/or with short-shorts.

Yo that girl Erica had quite the Reverse Ass Cleavage last night!

Reverse Ass Cleavage by gatsome January 27, 2011