[rand0]

His $6 could have been a bluff out of the gate but he could've been holding 4,5 or even offsuited low gap connectors such as 4, 6, and got lucky with straight draw or trips on the flop. Hell, he could've had a low pocket pair like 6,6 and flopped QUADS. If it was a straight draw, he could've caught his 2 on the turn for the big bet, or he could've even had 6, 2 offsuit and caught a boat.
I probably would've balked at a $100 dollar raise with only a pair of Queens and such a low board.