The multiplayer-related ones, like a lot of other people have said. I don't want to play the multiplayer on most games, so I don't even bother trying to get them. Even some of the Portal 2 co-op trophies/achievements (I get both at the same time 'cause I'm special) are kind of a stretch, even though I actually played the co-op. One of the stand-outs is the one you get for hugging three people on your friends list. I don't even have three friends on either my Steam or PSN friends lists, much less three friends that have Portal 2, so how the fuck am I supposed to get that without going out of my way to cheat, huh? The one for going through the tutorial with a friend who hasn't played before is even worse because it's so circumstantial.