A tie between all of them, plus wearing saggy pants.
But I think the worst thing a guy can do is to wear skinny jeans that are somehow also saggy. It looks like they couldn't get them on all the way so they just gave up and left the house like that anyway.
Whatever happened to men being men? Leave the concern for fashion and style to the socially-obsessed women. They have enough competitors, they don't need a whole extra fraction of another gender to worry about.
If I had to choose, it's skinny jeans. Men SHOULD NOTTTTT wear skinny jeans. I don't wanna see their junk (or the lack thereof ;P) all the time. Also, it makes them look feminine. Men don't look good when they look feminine. If I wanted to date a feminine person, I'd be lesbian.
I don't go for the unisex look. I haven't got anything against skinny jeans, but they are a little uncomfortable for most kinds of activity. And they were a girls' fashion trend first, so they give a unisex, metrosexual kind of look. Fine for movie stars, but the rest of us..
I don't really care...I think people should be allowed to wear whatever they want (within reason) without getting hated on.
And I'm sure guys aren't gonna like this, but every guy I know that wears skinny jeans either has a girlfriend or hooks up with lots of girls at parties (or both in one case). So jealousy may be a factor in the hate since most girls (not all) tend to like them...notice how no girl has chosen skinny jeans as a poll option yet.
It's not on here but the worst is meggings (men's leggings) that has caught on with some celebrities and leaked somewhat into the general male population. Leggings can be sexy on girls but not on guys in any way, shape or form.