Maybe getting the Play trophy in Little Big Planet. Though, I feel I'm forgetting something a lot harder.
Doing Crawmerax in Borderlands legit with only my friend as Brick was pretty damn hard. Luckily I was Lilith. Still think I'm missing something.
NO! I GOT IT! Portal advanced challenge gold medals. I got half before my progress reset and I said screw it. Took me two days of playing to get 9/18, and those 9 were the easy ones.
ALSO! Burn 'Em Out veteran in Call of Duty: World at War. That shit was just brutally unfair. Anyone who beat that game on veteran is my idol. I had to give up, it was just too fucking hard. Halfway through the campaign, it was twelve times harder than Modern Warfare 1 veteran.
(I might go back sometime this year and try and beat veteran. Masochism, activate.)