Finishing Stuntman for the PS2. With 100%. Christ that game was mind-numbingly hard. I just mean stupidly, ridiculously, throw you controller through the screen hard.
It was the sort of game that took me a few days to ge through a level, and by that point I would be so frustrated (there's only so far the "HELL YEAH I WON" can take you) that I wouldn't play it again for a month.
I let my brother play Stuntman once for about 20 minutes. He broke my controller...
I'm also proud of returning 'A Dogs Life' to the store (not proud that I bought it).
And I'm also proud that I played Kao the Kangaroo. That was a kick-ass game.