AKs - what to do, what to do?

[CheapFlop]

Poker Stars - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 6 Players - (LegoPoker HH Converter)

SB: $42.45
BB: $28.70
UTG: $53.50
<font color="black">Hero (MP): $50.00</font>
CO: $47.75
BTN: $51.80

<font color="black">Reads: </font><font color="blue">Just sat down, but in the 13 hands so far seen/played villain has shown to be an extreme lagtard, stacking off for $20 with 86o when he hit a pair of 8 on the flop to another player in a limped pot.

Is there any way I can call here?</font>

<font color="black">Preflop:</font> Hero is dealt K[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/spade.gif[/img] (6 Players)
UTG folds, <font color="red">Hero raises to $2.00</font>, CO calls $2.00, 3 folds

<font color="black">Flop:</font> ($4.75) 9[img]/images/graemlins/heart.gif[/img] 5[img]/images/graemlins/heart.gif[/img] 6[img]/images/graemlins/spade.gif[/img] (2 Players)
Hero checks, <font color="red">CO bets $2.00</font>, <font color="red">Hero raises to $5.00</font>, CO calls $3.00

<font color="black">Turn:</font> ($14.75) 3[img]/images/graemlins/spade.gif[/img] (2 Players)
Hero checks, <font color="red">CO bets $6.00</font>, Hero calls $6.00

<font color="black">River:</font> ($26.75) K[img]/images/graemlins/club.gif[/img] (2 Players)
Hero checks, <font color="red">CO bets $20.00</font>, Hero????