We all sit in a circle, place our hands on each other's knees, and try
to establish a rhythm by tapping each other's knees in sequence. This
is a very silly experience. First of all, just seeing every one else's
hands on every one else's knees -- it looks, well, weird. Then, I guess
because your hands are crossed over your partners', it's really somewhat
of a challenge to figure out whose hand is whose.
So far, in an intense meeting with a few friends in Amsterdam, we discovered that, depending on the degree of mutual sobriety, even putting hands on our own knees and maintaining an unbroken rhythm was challenge enough. We also discovered the "flea" variation: instead of putting your hands on each other's knees, you only put your fingers, raising your palm. Then when it's your turn to move, you kind of jump up off the knee, flee-like. The variation added a good sense of silliness as well as a good alternative to knee-hitting.
Some partially formed ideas:
Upon some signal that one person could give (perhaps by tapping with the back of the hand instead of the palm, or by tapping with a "thumbs up" fist) the third tap after that has to be a clap. Or some other way to insert the idea that, for example, if Tom is on my right, he and I are going to clap hands (his left to my right, the ones that are closest to each other, knee by knee)
Also wondered whether it would be more challenging if the group were singing/humming (as in Dum Dum Da Da) and tried to tap in time with the rhythm. It might be fun to figure out a three song repertoire (each faster than the last). Actually humming or singing syllables is a great way to get music going without people having so much performance anxiety. Or maybe it could even be done in rounds??? to something like Frère Jacques or Row Row Row your boat. Music is culturally based so it might not work with truly international groups.
What about introducing finger snapping in some way?
Or what if left hands were closed, right hands opened, but each time you tapped, you were supposed to reverse that?
Advanced Knees - wherein we explore the properties of interlocking circles