1. Halloween is coming
2. Possible publicity stunt
3. Copy cats
4. Definitely not Juggalos/Insane clown posse (the identifier would be the hatchet man silhouette; I am not able to post a pic of it right now, but you can google it)
5. There may be some weird bulletin board/forum for clowns and they are behind it.
And I know of two Juggalos on FR, but they shall remain anonymous (I am not one, though I listen to some of their songs via the girlfriend).