I was on an int'l 777 DEN-ORD in October of 2001 that had a w/b issue. While stopped on a taxiway (why it was identified then, I have no idea), the captain came back and asked some F passengers to move to C. As people started milling around, a guy flies out of Y demanding to know what's going on, throwing a general fit. I'm in the main section of C, watching 2 large male FA's start to crack their knuckles.

FA's get him seated, we immediately turn around for a gate, and get the guy and his bags off the plane and into the hands of armed men. Caused a 2hr delay.