Weird turn bet from fish into my overs

[TredWel]

SB is a complete and utter dummy. PT stats of 82/3/2.2

Party Poker 1/2 Hold'em (8 handed) converter

Preflop: Hero is CO with J[img]/images/graemlins/diamond.gif[/img], A[img]/images/graemlins/diamond.gif[/img].
UTG calls, UTG+1 calls, MP1 calls, MP2 calls, <font color="#CC3333">Hero raises</font>, <font color="#666666">1 fold</font>, SB calls, <font color="#666666">1 fold</font>, UTG calls, UTG+1 folds, MP1 calls, MP2 calls.

Flop: (12 SB) 2[img]/images/graemlins/diamond.gif[/img], 6[img]/images/graemlins/heart.gif[/img], 3[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(5 players)</font>
SB checks, UTG checks, MP1 checks, MP2 checks, <font color="#CC3333">Hero bets</font>, SB calls, UTG folds, MP1 calls, MP2 calls.

Turn: (8 BB) 7[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">SB bets</font>, MP1 folds, MP2 folds, Hero ...