When big events are held in places like the Pyramid or the Liberty Bowl, there are usually long lines to the restroom. Why is that? Do people all at once feel the need to use the restroom? No, I don't think so.
The restroom is a very popular place for females who are on a date and kids who are bored with the big event that their parents want to watch. Females tend to go to the restroom not to use it for its main purpose, but to discuss life issues and to freshen up.
Males go and take care of business and leave as quickly as possible to get back to the event or to continue trying to pick up girls. In my case, I attended a basketball game and I had an emergency, which involved a meeting with infamous restroom lines. So I stood in line as long as I could but I couldn't stand much longer, so I went to the front of the line and offered the guy standing there a few bucks to let me cut in line.
What would stop the long lines at the restrooms during a big event? Should more restrooms be installed? I don't think so. There is not a shortage in restrooms. People always overuse resources that they don't have to pay the opportunity cost on. If the owners of the arenas start charging people for the use or the time spent in restrooms, that would cut the lines in half and put an end to the restroom congestion.
I'm sure no one would pay to go the restroom to look in the mirror or discuss their date and what he/she is wearing. Only those who must use the restroom will pay the fees to do so. And for those people who attend with low incomes, they would prepare themselves by using the restroom before they come or they won't eat or drink at the event. By placing a price on restroom time, this would make people evaluate their options and choose the one that has the most value. One, finding out how strong their bladder is or two, paying the fees to ease their suffering.