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An extreamly fat human.
That girl with the kankles is fatty fatty boom batty
by alisha November 29, 2002
Also used in drug references
"I'll tell you what you need is a fatty boom batty blunt, then you'll be seein' a sailboat, an ocean, and some of those mermaids doin that lesbian shit!"

-Jay, as played my Jason Mewes
by Double Threat January 16, 2004