A promiscuous woman who engages in coitus with many different partners and thus should attach a mattress to her back
to increase time efficiency.
Ay Wortimer! Do you recall that matt back we double-teamed last Friday?
matt back: define #2
A large fatty growth that makes your back and head look like they are one solid piece. Often it makes you walk like a penguin.
Move, your Mattback is covering the sky.