I observed the following hand at a high stakes UB table, and almost everything seemed to go against my limited common sense. Can some of the experts explain what the thought processes are here?

6 handed.
Player A is BB and has 90 BB, player B is UTG and has more than a full stack. Player B makes it 3BB. Player A calls. Flop comes 268 rainbow. Player A bets pot, player B raises pot, player A moves in, player B calls.

A had K6, B had JJ.

What do these guys put eachother on?? Why does A think that B will lay it down and why is B not afraid of 2pr, set...?

Related question: I notice quite often that people at the high stakes game do play tptk and overpairs for their entire stack, or, more correctly, for a stack of the size of one buyin. Surely, if the game is shorthanded then these hands go up in value, but still?

As a contrast, I saw the following hand between Hassan Slask and Matusow. This was the first orbit Matusow played at the table.

Hassan raises, Matusow calls. Flop comes rags. Hassan bets pot, Matusow goes allin. Hassan folds, showing KK. Matusow shows AA.

Pieter

Player A is thinking that if Player B does does not have a pocket pair his pair is good so he bet the pot.

Player B is thinking his overpair is good so he raises.

Player A is thinking Player B is putting a move on him and is trying to take his pot so he goes all in. Also if he is behind he gets to see the rest of cards without the chance of out guessing himself.

Player B is so glad that player A went all in because the odds or good that his over pair is ahead.

Wow, do I really think I know what they were thinking lol.

Hmmm

Basically, being aggressive is good.

Both these players are being aggressive, so K6's bet doesn't indicate much, and JJ's raise doesn't indicate much (since they'd both also make these moves with draws etc).

Some percentage of the time you get something that looks daft, like K6 vs JJ.

Alternatively, K6 is a rich idiot, and JJ knows this