Whats my play in this bar situation?

[ChrisCo]

It is graduation weekend in my college town so naturally the bars are as crowded as ever and everyone is letting loose. My brother just graduated with several of his friends and I went out to celebrate with him. I am 19 right now but one of my friends work there and was able to sneak me in.

So I am there for about 1.5 hours and have had about 5 drinks and need to go to the bathroom. At this bar there are only 2 different bathrooms that are a single only so naturally there is a long line. I get in line behind about 10 people and wait patiently and check out any of the girls walking around. I get to the front of the line and am waiting for about 10 seconds when the guy behind me goes around me and starts knocking on the door. This man is about 25 and roughly 250lbs, but no muscle. I am annoyed by this because A. it is just a dick thing to do and B. he had only been in there for ten seconds. The man walks out of the bathroom not saying anything and I walk in and lock the door behind. I don't even get to unzip my pants before I get this guy banging on the door now even harder.

How do you handle this situation?