It was my party and it wasn't bad until a girl we nicknamed "crazy Jessica" showed up. It was a Christmas party and I'd done a lot to make it awesome. I set up the Netflix fireplace on a tv, had a whole playlist of Christmas rap songs, Christmas lights hung up around the house, and the front door had been decorated like a Christmas present. So near the end of the night my roommate (who had dated crazy Jessica a year prior) got drunk and asked her to come over. She didn't know where we lived in the apartment complex so he told her our front door looked like a Christmas present. Sure enough she scours the entire complex to find our door and knocks. By this time the party had died down and the only guests left at the party were these two girls. So my roommate goes outside after realizing his horrible mistake and tries to talk a belligerent drunk, crazy Jessica into going home. Suddenly we here, bump, bump, bump, on the door and then yelling. The door flies open and my roommate tries to get back in the door as I see Jessica's hands hit the ground whole she tries to grab at his legs to keep him outside. He shuts the door behind him and my roommates and I give him a look -he realizes he's betrayed us- we tell him he's too drunk to deal with this right now so we send him to bed. For the next hour or so we hear Jessica yelling through the door and crying for us to let her in. Meanwhile the our two lady guests are trapped inside because our apartment only had one exit. So we waited and peeked out the peephole after a while and she wasn't there anymore. A bit later she called to apologize for getting blood on our front door, because apparently the three bumps we heard was her bashing her ahead against it.

tl;dr: Crazy Jessica tried to break through our front door using headbutts.