Villain here is a certifiable maniac - plays most hands, likes to donk bet into pre-flop raisers (a lot), likes to overbet shove at seemingly random times.

On an earlier hand he donk-bet the flop after calling my pfr OOP. I called the donk bet (77 on a Q-high flop); He then overbet shoved the turn - I folded and he showed a flopped set.

I've also seen him show down air after donk-betting a PSB on the flop and/or turn.

Hand #1383011513001158: Chelsea (6-Max) 11513
Seat 1: hounddog64 (308.80 in chips)
Seat 2: 14U2NV (226.35 in chips)
Seat 3: robalai (107.20 in chips)
Seat 8: stickdude (135.20 in chips)
Seat 9: waywaybehind (142.50 in chips)
Seat 10: seed420420 (33.50 in chips)
waywaybehind: posts small blind $0.50
seed420420: posts big blind $1
Dealt to stickdude [ ]
hounddog64: calls
14U2NV: folds
robalai: folds
stickdude: raises to $4.50
waywaybehind: folds
seed420420: calls
hounddog64: calls
*** FLOP *** [ ]
seed420420: checks
hounddog64: checks
stickdude: bets $12
seed420420: calls
hounddog64: calls
*** TURN *** [ ]
seed420420: checks
hounddog64: bets $50
stickdude: ?????

He could have a set, he could have 87, he could have complete air here.

What's my play?

go broke

I go broke here against this kind of player every single time, or as someone else says, I double up.

Also, fwiw, start raising up the donk bets, he has a set almost never and doesn't like/want to check when OOP as it feels alien to maniacs to do anything other than fold or bet.

Youre obviously playing guessing games with guys like this because its almost impossible to put him on a hand, but you have to fight back at some point and not just give up and wait for the nuts. This looks like the hand to fight back with. Shove it all in.