Best with a relatively large group. All but two players join hands forming a human chain. One of the two remaining becomes the Doctor and stands so that they cannot see the group or leaves the room. The other then attempts to put the group into a knot by getting players in the chain to weave over and under each others arms and legs without breaking their hold on each other. When ready, the group calls out “Doctor! Doctor!” and the player who was selected to be Doctor then has to work out how to unravel the knot again without breaking any part of the chain.