What?

Played today. Played loose and relaxed. Up and down. Chipped up $200 over my buy in. Four hands until I leave to pick up the kids. Look down at 33 on the button. Utg raises to $13. Five of us see the flop including the big blind. Flop brings 33Q. Super gin!!!! Now to get paid. Big blind bets $20. Middle position calls. Now all the books and blogs say I just call here. So I did Turn is a 2. Bb bets $20. Middle guy class. Blogs and books say call so I do. River is a 9. BB makes it $45. Middle guy pauses a sec and calls. I am confused as hell What do they have? I make it $100 after fake deliberation. Bb thinks a bit and moves in. The middle guy tanks Tanks a long time. He finally calls. I cannot raise him in due to the bb not having enough to reopen the betting. I call and immediately table my quads. I really wanted to know what they had. Must be quads over full house at least. Right? Bb had KK. Played itbso bad. Other guy had had AQ. Just needed one three