The laughing thing annoys me too. Or people that will laugh for entire scenes rather than just laughing at certain jokes...
When I go to movies up north in Chicago... especially the south side... blacks do a pretty good job of ruining movies... I know it's a "stereotype" but they seriously do talk to the screen during suspense/thriller/horror movies and they get out of control in comedies.... I've witnessed it first hand. Most everywhere else that I go watch movies it doesn't bother me because it's just one or two people yelling things out... But in the south side of Chicago it's the entire theatre and it's impossible to watch a movie like that.
I also hate loud eaters... people that chomp away on their popcorn... It's amazing how inconsiderate people are.