100nl JJ oop against unkown deep

[kaz2107]

No Limit Holdem Ring game
Blinds: $0.50/$1
6 players
Converter

Stack sizes:
UTG: $177
Hero: $272.67
CO: $174.10
Button: $228.20
SB: $100
BB: $141

Pre-flop: (6 players) Hero is UTG+1 with J[img]/images/graemlins/heart.gif[/img] J[img]/images/graemlins/club.gif[/img]
UTG folds, <font color="#cc0000">Hero raises to $4</font>, <font color="#cc0000">CO raises to $8</font>, 3 folds, <font color="#cc0000">Hero raises to $27</font>, CO calls.

Flop: 9[img]/images/graemlins/club.gif[/img] 3[img]/images/graemlins/heart.gif[/img] 9[img]/images/graemlins/spade.gif[/img] ($55.5, 2 players)
<font color="#cc0000">Hero bets $31</font>, CO calls.

Turn: T[img]/images/graemlins/diamond.gif[/img] ($117.5, 2 players)
Hero ????

Reads and thoughts...
Next to nothing on villian except he bought in for like 160 bucks like 4 hands ago. other then that there isnt much. Tha pot is pretty big and i have an over pair against a likely donk (i sorta assume this due to him buyin for a weird amount and that i havent seem him bfore and unkowns at abso r typically tha donks)

do u like tha 4 bet given we r deep and im oop?!?!?! wut r ur thoughts on EVERYTHING about this.