I'm dutch with a pretty good grasp of english and never knew "munt" was slang or offensive. You learn every day.
Very, very few Americans would even know any meaning for the word "munt". But if they heard it spoken, especially if in the context of money or the herb (mint), they would assume the speaker said "mint". Also, I don't think it's a bit of a stretch to imagine that munt became mint in England a few hundred years ago...
Some of the people here need to lighten up about names. Perhaps we can start with the assumption that a word isn't being used negatively until it's demonstrated otherwise.