A very unattractive and fat person. Usually said when the person is thought to be atractive but when you see a picture they are ugly.
Kyle: Hey this hot girl is sending me a picture of her!
Jason: Let me see!
Kyle: Just received it, take a look!
Jason:....She looks like a wooly mammoth!
Kyle: FTW
Once a woman has passed the age of being a "cougar" (generally 50 plus) she is considered a wooley mammoth. She can still pull guys in their 30s as they think she may still be a coug because she takes good care of herself and looks like she's still in her forties.
Dude, thats no cougar, she's way over 50, she's a wooley mammoth.
Sex act where a hairy males back is shaved then the shavings are taken and placed into a condom which the male wears during sex. After he ejaculates into the condom the mixture is poured on his partners back.
Brendashaved my back and then I wound up cloning the woolly mammoth all over her back.