When playing low stakes I've seen many plays that are not just borderline insanity, but go well beyond. It's not at all uncommon (for example) to see people making plays where I wonder if they know they need to use two holecards to make a hand.

But there's one hand that you guys just have to explain to me. I can't understand what kind of thought process goes into making this play.

I open KJT8ss UTG, CO calls and everyone else folds. Flop comes J7A 2-tone, I have backdoor FD and bet. CO calls. Turn is an offsuit 4. Not the greatest barreling spot, but something tells me to bet again, and I do, and he calls. River is an offsuit Q, so I make my straight and bet 2/3 pot. Never mind my play for now, it's at least reasonable.

What I find hard to understand is that CO calls the river bet and shows T983ss (with the only suit that was never on the board).

Flop call is crazy. Turn call is again crazy. But on the river.... he thinks for a while and calls with T high. I had to stare at the hand for five minutes to convince myself that it was actually real.

Someone please explain the thought process behind his play here. Or am I somehow misreading the hand? To me it looks like the best hand he can make is AQJT9. (ok so technically it's A high, but whatever) Does he really think I get here with 9 high or worse that often? Or what's going on?