When you're fighting Arcanist Doan; the final boss in the Scarlet Monastery Library wing, he will often sheep you. This particular sheep lasts about 20 secs and can be very annoying if he sheeps the tank or healer. However, if you simply jump while sheeped it breaks immediately.
I've done this twice and a group member did it too, so i'm pretty sure it works.
It might also work for player sheeping, but i don't think it will.
Tested on 1.11.2