Did you see this joke in written form, or did you hear it out loud? If the final word is actually written as "men well," then I don't understand the joke either. If it merely *sounds* like "men well," then my guess is that the word you're hearing is actually the name Manuel. This is a a common name in a few different languages, but it's also very similar to the English word "manual," which means an instruction book. It doesn't seem like a very funny joke, though, either way...

The name is "Manuel": a common Spanish given name which resembles the word 'manual'.