Also used as "Grungleshit, Grunglefuck, and Grungleschlaug"
When something is obnoxiously, or intensely rough. It is also used as an obscenity when something is wrong, similar to saying, "Ah shit" or "oh fuck".
I'M TAKING A GRUNGLESHIT!
He fucked me last night and the bed moved an entire 5 feet away from where it should be, he grunglefucked me.
That is grungleschlaug!