Overpair against passive donk

Previously the villain had played v. passively limping in UTG with QQ and just calling raises on each street from another player, a king had landed on the flop though.

Im not sure how to read the river bet...has he got something here or is this a bluff? My feeling is that because he has played so passively if he had something he would more likely make a weak bet here rather than shove

PokerStars No-Limit Hold'em, $0.05 BB (4 handed) - Poker-Stars Converter Tool from FlopTurnRiver.com

UTG ($8.93)
Button ($5.32)
SB ($8.10)
Hero (BB) ($13.46)

Preflop: Hero is BB with 7http://www.flopturnriver.com/phpBB2/...es/diamond.gif, 7http://www.flopturnriver.com/phpBB2/...iles/spade.gif
1 fold, Button calls $0.05, SB calls $0.03, Hero raises to $0.25, Button calls $0.20, 1 fold

Flop: ($0.55) 2http://www.flopturnriver.com/phpBB2/...iles/heart.gif, 3http://www.flopturnriver.com/phpBB2/...es/diamond.gif, 2http://www.flopturnriver.com/phpBB2/...miles/club.gif (2 players)
Hero bets $0.40, Button calls $0.40

Turn: ($1.35) 8http://www.flopturnriver.com/phpBB2/...iles/heart.gif (2 players)
Hero bets $1.30, Button calls $1.30

River: ($3.95) 5http://www.flopturnriver.com/phpBB2/...miles/club.gif (2 players)
Hero checks, Button bets $3.37 (All-In), Hero ???

I fold this one; I don't think he's bluffing.

Looks like a slow-play trap from the outside.. I think he's on a draw and limped out on you.. If he's passive, you're right when you say, "why shove all-in"

This is NOT a bluff.

Well, it is a bluff, in the sense that he's only got a medium pp (likely). But you can't even beat that.

Fold. Reload. Get his stack with TPTK later.

easy fold.

if anything, you cant even beat a pair of 8's lmao. but surely he's got more than that

I bet a little smaller on the Turn (2/3 PSB) and then check-fold to this shove. This is frequently a calling station's approach to value when you don't cooperate by betting for them...