2.) When you consume large enough quantities of alcohol that you enter a state where you fall and cant get up, need adult diapers, and have trouble getting an erection, much like a Grandparent.
"Dude what's this awesome music?"
"That my good chum is uncut dirty grunk!"
"I think grunge is good and all but its so depressing"
"All you need my friend is a hot injection of groove... GRUNK IT UP!"