Every Monday I go swimming; every Monday I get pissed off.
There is only really one time that I can go swimming in a week - Monday evening. The thing is, Monday evening is the only time that a lot of other people can go swimming. It makes for a busy pool, especially as it is only open to the public between 8:35pm and before 10pm (when the pool closes).
On a Monday, there is a swimming class that gets out of the pool at 8:35pm. Once they get out, where do they head? Straight to the showers. There's the first obstacle ...