Linguistic Flexibility

This comic about adding a prefix to the verb “blow” reminded me that we have a tendency to wonder about the form of a word when we add a prefix to it or change the context. Does it change, or does it stay the same?

I’ve heard people use “mouses” when referring to computer mice. And when making backups, I’ve heard both “backed-up” and “backupped.”

Maybe you can think of an example or two. Put it in the comments.