This glitch only occurs whenever two people are playing together in any server. But if one person's sanity is low and going insane, and the other's sanity is perfectly fine, the rabbit has it's arms completely black, (like how they are supposed to be when your character is insane.) Their bodies are completely fine the way they should be. Puffy white and adorable. If you are the player that has low sanity, the bunnymen are just black and how they should be when insane. If you are the player who has perfect sanity, that's when the glitch occurs. I don't know if you have to be a certain character for this to happen. But for me, I was Wolfgang, and a friend was Wilson.
It's a bit hard to explain, but it's easy to make the glitch occur. If this isn't a glitch, or such--.. I'm terribly bad at explaining, but this is just bothering for some reason, haha.
At a base from home, and a friend was insane from picking up dark petals, (we needed for Nightmare fuel!) We have a few farms for Carrot homes, and bunnymen easily waddle around. He came back, and sanity was low, and that's when these glitches occured.