I gained about 10 pounds, which was good because I was about 10 pounds underweight before. I didn't eat much in college though, so I chalk it up to the fact that my body didn't really develop until I was 18. I'm still about the same weight now as I was during my freshman year.
And YES it does happen to guys! I saw this guy I went to high school with at a party at another school one night... In high school he was a toothpick, but when I saw him at this party, he was at least 20-30 pounds heavier! Probably all the beer...