Born a Crime, Chapter 12

Murphy's Law: "Anything that can go wrong will go wrong".

In context, this refers to Mom's determination to "not" have to continuously buy Trevor clothes. Trying to stay ahead of the game didn't work out.

And of course, Murphy’s Law, the year my mom started buying my clothes too big was the year that I stopped
growing. So now I was never going to grow into my clown clothes and I was stuck being a clown.