I wanted to stroke a horse, so I instinctively held my hand out for it to smell first, like you would with a dog, and it tried to eat my hand. Its teeth were clamped down, and it wouldn't let go. It hurt, and I was starting to panic, so the only thing I could think of was sharks and how they hate being punched in the nose, so I tried lightly hitting it (didn't want to actually hurt it) on the area above its nose, several times, but it didn't care. It eventually let go, I imagine, when the 'food scan' in its brain finished and the result was "no food detected".