You have to know how to hold it.
You hold one had across it’s back, pinning the wings with your grip. The other hand holds the feet firmly against the belly, knees bent. You place it on the stump backside down, slide your hand from under it, keeping it pinned firmly with the other hand. Grab the hatchet. Just before you swing, you lean forward a bit and let go a slow, frothy glob of spit to land right above its head. You only get it distracted part of a second, so the swing has to be swift. You have to really mean it, so the hatchet goes all the way through.
Yup, gross. That is why I only watched the one time I was told to.