The guy has a tiny 3bet range. So he's probably only 3betting qq+, and maybe ak, so I called preflop for set value.
Then let him barrel a couple of times and on the river I potted it like a moron. I should have bet something that an overpair would call, like $3 or $4....

iPoker - $0.10 NL (6 max) FAST - Holdem - 6 players
Hand converted by PokerTracker 4
BB: $10.67
UTG: $12.84
MP: $10.00
CO: $12.70
Hero (BTN): $14.17
SB: $11.53
SB posts SB $0.05, BB posts BB $0.10
Pre Flop: (pot: $0.15) Hero has 5♥ 5♦
fold, fold, fold, Hero raises to $0.20, fold, BB raises to $0.65, Hero calls $0.45
Flop: ($1.35, 2 players) 8♠ 5♣ 9♥
BB bets $0.80, Hero calls $0.80
Turn: ($2.95, 2 players) 6♥
BB bets $2.21, Hero calls $2.21
River: ($7.37, 2 players) 9♠
BB checks, Hero bets $7.10, fold
Spoiler
Hero shows 5♥ 5♦ (Full House, Fives full of Nines)
Hero wins $6.88