QotD: Try making up the rules to a game where you tie knots in a yo-yo string just to see if you can get them out:

Any number may play KNOTTY YO-YO, from beginners to experts.

Player A begins by tying a simple overhand knot in the string. Player B adds a second overhand knot, attempting to tighten both knots using the momentum of the yo-yo. Player C repeats the knot, and so on, until the play comes back to Player A, who then attempts to untie all the knots.

If successful in untying all knots, Player A then ties the next knot indicated (see below), and play continues as before. In the event Player A cannot untie a given sequence of knots, the play moves to Player B, who repeats the knot that stumped Player A, and play continues as before, with Player B attempting to untie each sequence.

BEFORE PLAY, players must agree on instruments allowed to facilitate untying knots. While purists stick to fingers and teeth, others may wish to allow a fork. Skewers and ice picks should be avoided, due to the almost certain possibility that someone will poke their eye out.

In the standard game, knots must be tied in the following sequence:
Simple overhand
Double overhand
Triple overhand
Figure eight (or Flemish knot)
Multiple figure eight (three loops)
Stevedore’s knot (combination overhand and figure eight)
Eye knot
Figure eight eye knot
Square knot (sailor’s or flat knot)
Granny knot
Rogue’s knot
Surgeon’s knot
Bow knot
Double bow knot

For less experienced players, the game may be played with hitches, which are easier to untie. (Remember that a broomstick or something similar will be required for hitches and bends.) In this case, the sequence of play is as follows:
Half hitch
Timber hitch
Timber hitch with half hitch
Killick hitch
Fisherman’s bend (anchor bend)
Simple slip knot
Double slip knot
Slippery hitch
Running knot with a half hitch
Clove hitch
Midshipman’s hitch (two half hitches with a twist)
False lark’s head
Lark’s head (cow hitch or baggage tag loop)
Double lark’s head
Triple or interlocking lark’s head
Crossed lark’s head
Racking hitch with one inward twist
Racking hitch with two inward twists
Cat’s-paw

For more complicated play, two yo-yo’s may be used:
Two rope square knot (reef knot)
Double overhand
Flemish knot
Figure eight hand knot
Sheet bend
Weaver’s knot
Carrick bend
English knot

A continuation of this complicated play begins with a knot to join the two yo-yo’s (at the finger loops, so that the discs remain on either end). This knot will remain, not coming into further play (In other words, don’t untie that one, silly).
Standing bowline
Figure eight or false bowline
False bowline with a half hitch
Spanish bowline
French bowline
Lasso or Honda knot

Another variation using two yo-yo’s tied as previously:
Single chain twist
Double chain twist
Sheepshank
Catshank
Dogshank
Overhand knot with sheepshank
Jury knot with sheepshank

For those who just can’t quit:
Tom Fool knot
Shamrock
Jury mast knot
Double jury knot
Oriental knot

For those who REALLY can’t quit: get a copy of “Knots and How to Tie Them” by Walter B. Gibson. He will astound you (and will explain how to tie everything listed here—drawings included). If you learn to tie every knot he lists, you will be declared the winner!