The alpine butterfly is a secure loop in the middle of a length of rope. It is secure when loaded in any direction and does not jam. It can also be tied near the end of a rope as a secure substitute for a bowline. Unlike the bowline, the alpine butterfly will not shake loose when unloaded. It is widely known among climbers but under-appreciated outside of that community. Grog describes a method of tying this knot around the hand. I prefer the twist-twist-tuck method.