What would you do?#114 - Four flush rivered board facing overbet shove

Full Tilt Poker $0.25/$0.50 No Limit Hold'em - 9 players
The Official DeucesCracked.com Hand History Converter

MP1: $69.95
MP2: $113.10
Hero (CO): $67.40
BTN: $49.60
SB: $67.00 - 29/29/ - ATS / 33.3 3BET / inf AF @ 7 hands
BB: $50.65
UTG: $39.20
UTG+1: $85.50
UTG+2: $23.45

Pre Flop: ($0.75) Hero is CO with 4s Ad
5 folds, Hero raises to $1.75, 1 fold, SB calls $1.50, 1 fold

Flop: ($4.00) As Ks 8s (2 players)
SB bets $2.50, Hero calls $2.50
Trying to manage the pot size here.

Turn: ($9.00) 3d (2 players)
SB bets $5.50, Hero calls $5.50
Again, trying to manage the pot size here.  Ideally, I want a cheap showdown.

River: ($20.00) 6s (2 players)
SB bets $57.25 all in, Hero ???


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Another bluff catcher hand. 3 streets of betting and the 4th spade comes out. The problem here is the SB overbet shoving. Either he's got the Qs or air. What hands can ever call him here other than the Qs? Am I a wimp for not looking him up? Are you calling here?
Hero requests TIME, Hero folds

Final Pot: $20.00
SB wins $19.00
(Rake: $1.00)