I was watching a hand and I think I would have either checked the river or mucked for the All-in.

The action on the Turn said to me that MP3 had very good hand. Of course, I wanted the BTN to call so I could see MP3's hand. I though MP3 had a set.

PokerStars No-Limit Hold'em, $2 BB (9 handed)

CO ($156)
Button ($212.05)
SB ($118)
Hero ($241.60)
UTG ($109.40)
UTG+1 ($95)
MP1 ($132.40)
MP2 ($332.45)
MP3 ($308.45)

Preflop: Hero is BB with , .
4 folds, MP3 calls $2, 1 fold, Button raises to $7, 2 folds, MP3 calls $5.

Flop: ($17) , , (2 players)
MP3 checks, Button checks.

Turn: ($17) (2 players)
MP3 checks, Button bets $10, MP3 raises to $20, Button raises to $40, MP3 calls $20.

River: ($97) (2 players)
MP3 checks, Button bets $40, MP3 raises to $261.45, Button calls $125.05 (All-In).

Final Pot: $523.50
Main Pot: $427.10, between Button and MP3. > Pot won by MP3 ($427.10).
Pot 2: $96.40, returned to MP3.

Results in white below:
MP3 has 2h 2s (four of a kind, twos).
Button has Ad As (two pair, aces and twos).
Outcome: MP3 wins $523.50.

Button needs a poker lesson.

I think he got one - a very expensive one at that

MP3 was way too passive. If I'm Button I'm definitely checking behind on that river and MP3 gets zip.

You can't check-raise and then go for another check-raise. WTF.

I gotta get my guts together and move up. Christ almighty.