Human Knots (or Dr. MixUp)
Everyone stands in a circle. Each person reaches across the circle with their right hand, and takes the right hand of someone across the circle.
Then everyone takes the left hand of someone else.
Then, without letting go of their grip, they untie themselves.
Dr. MixUp involves having one person not tied into the knot. That person goes around observing the mess, and instructing the participants on where to move to get untied. This is a great cooperative game!