99 Overpair Against a Bad Loose Opponent

[74o_Clownsuit]

Villain and I have quite a bit of history. He runs at around 50 vpip and every-so-often goes crazy with his holdings. He tilts very badly and when things aren't going his way he likes to open-push with his 50bb stack or whatsoever. In a nutshell, very erratic and loose.

He probably gives me almost ZERO credibility most of the time, especially because in one spot I called him all-in on the turn with just AK high... and won.

Full Tilt Poker - No Limit Hold'em Cash Game - $0.50/$1 Blinds - 6 Players - (LegoPoker HH Converter)

SB: $60.65
BB: $93.10
Clown (UTG): $129.55
MP: $96.80
CO: $120.20
BTN: $98.50

Preflop: Clown is dealt 9 9[img]/images/graemlins/spade.gif[/img] (6 Players)
<font color="red">Clown raises to $3.50</font>, MP calls $3.50, 3 folds, BB calls $2.50

Flop: ($11) 6[img]/images/graemlins/spade.gif[/img] 5[img]/images/graemlins/spade.gif[/img] 7 (3 Players)
BB checks, <font color="red">Clown bets $8.00</font>, <font color="red">MP raises to $22.00</font>, BB folds, Clown???

What's the best course of action here?