Villain is loves to call everything. I have seen him stack off with a mid pocket pair a little before.

Full Tilt No-Limit Hold'em, $0.25 BB (6 handed) Full-Tilt Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver Cards)

BB ($9.55)
UTG ($25)
Hero ($30.40)
CO ($17.10)
Button ($21.35)
SB ($24.75)

Preflop: Hero is MP with , .
1 fold, Hero raises to $0.85, CO calls $0.85, Button calls $0.85, 1 fold, BB calls $0.60.

Flop: ($3.50) , , (4 players)
BB bets $0.25, Hero raises to $4.25, CO folds, Button folds, BB calls $4.

Turn: ($12) (2 players)
BB bets $4.45 (All-In), Hero calls $4.45.

River: ($0) (2 players, 1 all-in)

Final Pot: $20.9

Can we ever fold here?

standard getting 4-1, BBFIDTS

You answer your own question in the OP saying how he's a donk who will stack off lightly. You beat everything that isn't a J here. BBFIDTS

Against a shortstack you played it perfect imo. Obviously this is much more of a decision if he had had a decent ammount of BBs. This is an instacall for sure though.