Describing a big fat sloppy pussy. So called because when you fuck one of these mush buckets, it sounds just like a welly in soft mud.
Dude 1: "That fat chick you used to go out with. She was good in the sack?"
Dude 2: "Yeah, real juicy - man she sounded like a welly in the mud some nights!"
Dude 1: "Awesome!"
by Wizards Sleeve September 4, 2006
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