An acronym commonly held to stand for "Product of an unspeakeable menage-a-trois", although there is some debate as to the meaning of the U. Simply stated, it referes to anybody who looks like a mix of any three celebrities or other things that should not have come together to create a person.
The term UMAT also pops up from time to time to suggest that three people are about to get it on.
"You say you're a PUMAT between JFK, Richard Kiel, and Andrew Dice Clay? What's a PUMAT?"
PUMAT between a drunk driver, a tree, and the grill of a CarmenGia.
PUMAT John Kerry, Kevin Sorbo, and Jimmy Johnson.
PUMAT between an Afghani hookah, a Chippendale chair and Cthulhu.
PUMAT of Marty Feldman, Peter Lorre, and Stephen Fry.
Erik the Red, Penny from Inspector Gadget, and Howard Stern. Yikes, I'd hate to see the P from this UMAT.