Usually used in relation to the breaking of the most basic social norms by one of extreme social awkwardness, effectively digging an even larger hole of social isolation than already exists.
Derived from the Italian 'Cavare' meaning 'to dig'.
Person 2: That is so Cavell.
Person 1: I don't want a mobile phone. I'm free from society's grip on my life.
Person 2: You are so Cavell.