Muggles, a play on the non magic folk from the Harry Potter series, are people who are not aware of the sport geocaching. Muggles can be threats to many caches as they can think cache are litter. Or vandalize them because they like to ruin others fun. Cachers generally try to avoid muggles when caching as they can draw attention to the cache.
Wait! Don't take it out yet...There's some muggles over there