[ThinkQuick]

3/6
Catch 89s in the big blind
drunk UTG straddle. This big guy works really hard to get last betting position in the hand, then bets and raises any 2. fun.
Anyways like 4 callers in EP-MP, all fold to SB who calls, as do I, and UTG gives the go-ahead.
Flop comes 567rainbow and I've got the nut straight.
SB bets. he's a good poker player but he's been winning a ton and it's really loosening him up.
I call
Drunk UTG raises (1/2 expected - he'll push on most low flops)
2 of the ep-mp players call
SB calls, I call. (Should I have limited my field more?)

Turn comes [567] 3 but same suit as the flop 7 (spades).
SB bets, I raise, UTG reraises, ep-mp s fold, and SB calls. I cap it, UTG and SB both call.

River pairs the board: [567 3] 6

SB checks, I bet, UTG raises, SB calls.
My friend (who saw my pocket preflop) gives me this look and nod to remind me that if I play like a wimp I ain't gonna win too much, and I reraise. UTG folds, and SB, who definitely knew the whole time that he'd have to show down a good hand to beat me, thinks a bit then says he has to call, and does so.
He asks if I have a straight, I say 'yah' and show it, after which he mucks.

Umm... What the hell did these guys have???
and is there anything I could have done better here?
especially based on what they might have had?