10/20 nl commerce casino, both stacks deep..

heads-up situation with two crafty players.

UG limps, MP raises $80 and it's folded to the button who re-raises the pot. It's folded to the og raiser who now calls.. The flop is as indicated:

A K 10 all spades..

7s8s goes into the tank and after less than a minute bets $500..

what is the thought process and how would you respond??