Opponent is running at 75/55 over about 60 hands. He goes crazy on some hands making huge moves on the flop and turn (about half the time) and fold the turn half the time. Calls or raises flop bets a lot.

Retard has $94 and I cover

1. I raise to $4 with [Js] UTG. Retard calls on the button, and shortie with a $2 stack is all in.
2. Pot $11, Flop comes [8s][7s]. I bet $9 retard calls.
3. Pot $27, turn comes . He has $80 behind, what's my move?

I'm checking and calling this down.