Sometimes, I hate...

Poker. Especially for a while after what (on the surface) appears to be a bonehead play on the part of an opponent pays off. And when it pays off against me, it puts me off my game -- or "on tilt", as it were.
The other day, I was doing fairly well in a 1-table DON[1]. Two players had already been knocked out, and the short stack was to my right (before me in line to act) and fairly nervous. Or rather, he had been opening up his starting hand requirements and pushing all-in with marginal hands, and had built his stack from 2 BB to around 5. This was late in the tournament, and I was bubbly[2]. I had around 10 BB when I got dealt pocket Queens in the small blind.
Action folded around to the nervous short stack in the dealer's chair. He pushes all-in. Now, his play until now has been erratic; any more so and I would say he was giving chips away... except when he actually had a hand, where he would flat call. Based on his play so far, I put him on either suited connectors[3] or a small pocket pair. I had been cultivating a tight-aggressive persona, so when I pushed over the top to encourage the BB to fold, he did.
If anything, I was giving Dealer too much credit. I was doing a happy dance in my head when he showed his 9-3 off suit. Dude was trying to steal a pot and I caught him with his hand in the cookie jar.
He pairs his 9 on the flop. I get a little nervous, because pair vs pair is a lot dicier than pair vs two unders, even with only 2 cards to go. No worries, I've got 8 cards in the deck which will improve my hand -- two of which will seal the deal -- to his 5. The turn is no help to either of us, save the fact it gives me a couple more cards that can't hurt me. Still, he has 5 outs, which will hit about 10% of the time.
Of course, the river card's a three, giving him two pair to my QQ. I fight my way back, but run out of chips against bigger and bigger blinds, finishing in 7th place, two out of the cash.

[1] Double-or-Nothing. A tournament format where all winners receive double their entry fee back. I.E., in a 10-player $1 DON; the top 5 players will win $2.
[2] A player near the last paid finishing position (both above and below) before the last non-paying position has went out is considered 'on the bubble'. The "bubble bursts" when the "bubbleboy" is left "outside the bubble".
[3] Two cards of the same suit which are less than 5 apart, usually less than 10. Combine the limitations of "Straightening cards" (pocket cards which, with a draw, put you in position to make a straight, but not much else) with the hidden strength of a flush draw and you get the idea.