Ah, you must have arrived recently, I take it? It's the name that's been given to a strange species of pokemon that showed up in large numbers last month, before vanishing nearly as suddenly. It's not known to the region and there's no information available on it, not even the proper name.

As for that, I imagine some people are concerned with it simply because they're covered with some sort of slime that they seem to have an uncanny tendency to get, well, everywhere, and it seems that quite a few people caught them while they were around.