As always, dreams have their own unique qualities. They are a mystery that only the dreamer can solve. That being said, there may be some commonalities that we can comment on here.
First of all, when you have a dream like this, consider the possiblity that you really do have to urinate. Oftentimes physical sensations and outside noises make their way into our dreams.
Otherwise, you can look at this image as symbolizing something in your life that is causing you pressure, something you need to get rid of. Ask yourself these questions:
Is it a public matter? Is it personal? Do you feel exposed? Vulnerable?
These types of dreams may be about the following:
Are you having a minor annoying conflict with someone in your life (i.e. are you "pissed off" about something)?
Do you need to speak your mind? Relieve yourself in some way?
Are you feeling trapped with no options about how things are going to go?
As Richard Wilkerson writes in Self Help Magazine:
"The key here, I feel, is not in finding a good place to urinate, but in learning ways of being in the predicament itself. This is what Jung calls a real symbol as opposed to a simple sign. A real symbol has the ability to hold the tension long enough for a whole new paradigm of consciousness to emerge."
As always, your thoughts and associations are welcomed!