is this karma?

This is so beyond me. Did you know that bunk beds are really really hard to make? I don't mean construct; I just mean getting the sheets arranged in a somewhat tidy fashion. They are so hard that I'm embarrassed to tell you how often I change the kids' sheets (still way more often than any guy in college, though, don't worry). So what I want to know is why, why, why is it inevitable that one of my children will wet the bed the very night I have changed the sheets? Fresh, clean sheets?