The washroom mirror dilemma

Why do people rush out of the washroom like a fierce hungry lion is about to pounce on them? 

I have always wondered why my colleagues turn to rush out of the washroom the moment another person steps into the next cubicle, or just to use the mirror. I don't believe its that awkward to run into your colleagues  at the washroom, lol

Is there a good reason why this happens all the time? I say no, there ain't no reasons. 

What do you think?