$22 - BB - Overpair 8's

[Insty]

Party Poker 20+2 No-Limit Hold'em Tourney, Big Blind is t30 (8 handed)

SB (t695)
Hero (t830)
UTG (t835)
UTG+1 (t720)
MP1 (t2545)
MP2 (t590)
CO (t820)
Button (t965)

Preflop: Hero is BB with 8[img]/images/graemlins/spade.gif[/img], 8[img]/images/graemlins/club.gif[/img].
<font color="#666666">4 folds</font>, CO calls t30, <font color="#666666">1 fold</font>, SB completes, Hero checks.

Flop: (t90) 2[img]/images/graemlins/spade.gif[/img], 5[img]/images/graemlins/club.gif[/img], 4[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
SB checks, <font color="#CC3333">Hero bets t80</font>, CO is all-in t790, SB folds, Hero ??


CO had been limping fairly regularly and had only shown down Q9 so far.
CO's bet really made no sense to me. The only thing I could think of was that he had somethink like A4 or some overcards like KJ and was trying to push me off my X5. But he could also have anything from 22-QQ. Where 66 and 77 are the only hands I beat.

Easy fold? or should I be thinking about calling here?