Party 1/2 How can you call this river?

[ghostface]

I dont have the hand history so I dont remember a few of the cards, but they dont help barons hand.

baronzeus is MP3 with 66

all fold and he raises, button or co 3-bets and the blinds fold

Flop: AJ7r

check, check

Turn: maybe a T

check, check

River: x probly lower than a 6

check, bet, call

WTF?

What can he possibly 3-bet PF that you are ahead of here? KQs is the ONLY thing that comes to mind.