It has no real definition, but it's derogatory and can describe a skank or someone that your friend has already fucked, sloppy seconds.
Greg: Hey Tom, how are you? I was thinking, I sure wouldn't mind if you fucked my ex-girlfriend Vicki.

Tom: No way! Do you think that I would fuck that piece of slunkmeat?
by Tom January 30, 2004
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A large, usually unattractive saggy breasts.
"Damn did you see Mary's boobs??! Girl got a whole lotta slunkmeat"
by Donnie Larko February 28, 2017
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