When someone is antisocial, they're either rude and unmannered or they avoid other people. Either way, they're not the life of the party.
This is a word that describes people and behaviors that are not very welcoming to others. Yelling, swearing, pushing, and generally being a jerk are all antisocial behaviors. Being a hermit and avoiding contact with other people is antisocial, too. Though this is a negative word, it's not entirely bad. We all need to get away from others once in awhile, and people who seem antisocial may just need a little space.