Eye contact while laughing
According to some research, usually, most people, when they laugh in a group setting, look at the person they gravitate towards the most when laughing. This does not relate to anything romantic, it could be someone you are close with as a friend or just the person in the group everyone likes.
Do not worry though, it is not an exact science, so if no one is looking at you when they laugh, do not take it personally. But it is a very common thing to happen, so it is a good indicator of how people feel about you and others around them.