A term used to described an overpopulated social setting, i.e. bars, clubs, lines at Disney World, men's bathroom, etc. The setting being so packed that male genitalia, regardless of intention, are constantly rubbing on the buttcheeks of surrounding individuals.
" Man there are so many people in here tonight, it's balls to buttcheeks."

"We went there last night, the place was packed balls to buttcheeks."
by Archibald M.W. Pinchback February 19, 2012
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