backboobs

An excess of fat that engulfs the bra strap of a female so much so that it appears that she has a set of "backboobs."

"Dude, check out the backboobs on that he/she!"
"Omg, it's like she has four boobs.."

Backboob

A backboob is a set of boobs that fat women's rolls form or their backs.

Look at that lady, she has a massive set of backboobs.