When giving a piano lesson yesterday, my student came up with this for an excuse for repeating the mistake that he had made, even though I had already demonstrated to him what the mistake had been and how he should correct it. "I am duplicating my mistake so that I know what I did wrong."
I thought that it to be funny enough that I wrote it down.
A number of years ago, a student told me in a classroom that "I can't sing because my finger hurts!"
Anybody else got any zinger excuses that people have given to you or that you have heard that have been given?