This wasn't a mistake, I did it on purpose.
Our group was working on Utah Phillips' Faded Roses of December, and instead of singing:
"I'd rather have a heartache to remember, than a fickle love that doesn't mean a thing,"
"I'd rather have a hardon to remember, than a feeble f*** that doesn't mean a thing."
Now my wife is afraid to sing it in public, because my lyrics are easier to remember and she's afraid she'll sing them by mistake.