A false friend is a word that looks the same in two languages, but means two different things.
Buen probecho is Chamorro for "you're welcome."
But it is borrowed from the Spanish phrase buen provecho, which means "good appetite!"
I would have loved to be there the moment one of our ancestors decided that "good appetite" would become "you're welcome" in Chamorro!
As none of this is documented, we'll never know how this got to be.