Love to hear how you would play as Set boy.
BB is tight aggressive and raises most hands he plays.

Party Poker No-Limit Hold'em, 50NL$ BB (6 max, 6 handed)

saw flop|saw showdown

BB ($89.15)
UTG (aka Set Boy)($50.80)
MP ($28.85)
CO ($42.90)
Button ($54.75)
SB ($74.95)

Preflop: SB posts a blind of $0.25.
UTG (aka Set Boy) raises to $1 with , 3 folds , SB (poster) calls $0.75, BB calls $0.50.

Flop: ($3) , , (3 players)
SB bets $0.5, BB raises to $2, Set Boy raises to $5, SB folds, BB calls $3.

Turn: ($13.50) (2 players)
BB bets $5,

Set boy???
What could BB have to call the reraise then lead weak?

Gross. Since JT is a real possibility, call and hope to fill up. Call a reasonable river bet or bet if checked to.

AA or QQ probably isn't the case since BB is TAG and would have raised PF, so I'm thinking his strongest hands are either AQ or A9 (with or without the diamond draw). If in fact 2 pair, you're vulnerable to the higher boat if the River pairs. You're also vulnerable to the diamond draw. Raise to $20 and make him pay to see it.