How did I play this JJ? I would have folded turn vs any normal size bets, but his bets was so small that I couldn't get myself to fold. Is that a mistake?

Also, what do you call it when you have JJ under the K? Like underpar if its under them all, something similar like that, is there a name for it?

PokerStars - $0.02 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4

BTN: 100 BB (VPIP: 31.58, PFR: 26.32, 3Bet Preflop: 0.00, Hands: 21)
SB: 360 BB (VPIP: 14.73, PFR: 9.40, 3Bet Preflop: 4.69, Hands: 325)
BB: 206.5 BB (VPIP: 12.28, PFR: 7.02, 3Bet Preflop: 2.20, Hands: 230)
UTG: 105 BB (VPIP: 19.54, PFR: 13.79, 3Bet Preflop: 0.00, Hands: 89)
MP: 162.5 BB (VPIP: 30.23, PFR: 25.58, 3Bet Preflop: 8.33, Hands: 46)
Hero (CO): 102.5 BB

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has J J

fold, fold, Hero raises to 3 BB, BTN raises to 9 BB, fold, fold, Hero calls 6 BB

Flop: (19.5 BB, 2 players) 8 K 2
Hero checks, BTN bets 10.5 BB, Hero calls 10.5 BB

Turn: (40.5 BB, 2 players) 7
Hero checks, BTN bets 13 BB, Hero calls 13 BB

River: (66.5 BB, 2 players) 7
Hero checks, BTN bets 21 BB, Hero calls 21 BB,

yeh I'd probably call like you did, you would think he would bet bigger if he had a K or better, maybe he's playing QQ like this though

not really sure if there is a name for what you asked

I would call this an underpair, but I googled it and apparently a lot of people only use the term underpair if your pocket pair is lower than all three flop cards? Who knows.

The turn call is close when the opponent bets larger but I don't think I'm folding to such a small turn c-bet in this spot.

I fold river as played, but even that's kind of weird getting 4:1. He has to triple barrel a good portion of his Ax's for a call to be profitable. I've been messing around with some ranges in Equilab -- I assume he bets AA-KK, 88-77, AK, and KQ. Depending on how wide you think he 3-bets PF, I get an answer that says he needs to bet river with missed Ax here between 30% and 45% of the time, which seems a little optimistic.

This looks fine to me.

I think you could consider a fold to a larger river bet, but I can't fold here for a 1/3 pot sized bet. The Jh in your hand hurts, since it means villian can't be barrelling off with AJhh, but I still can't fold this for 1/3 psb. I do expect to lose a lot of the time though.