Good party trick

[Halcyon]

Nope. Rotating the head instead appears to reproduce the effect though.

No can't seem to get beyond about 90 degrees with the head either, but that is each way, unlike this dude inky linky

you guys must do a lot of yoga?

[hyperD]

It probably explains why ballerinas are unable to write an autograph for you during a performance of Swan Lake.

[TimberWolf]

No can't seem to get beyond about 90 degrees with the head either, but that is each way, unlike this dude inky linky

you guys must do a lot of yoga?

Can you do this one then?

Place a notepad or something on the palm of your hand. Now rotate the hand, without rotating your trunk (cue elephant joke). Can you rotate it through 360 degrees? 720? Even more?

[NickFitz]

Place a notepad or something on the palm of your hand. Now rotate the hand, without rotating your trunk (cue elephant joke). Can you rotate it through 360 degrees? 720? Even more?

About which axis?

Can we use quaternions? I don't want to end up suffering from gimbal lock

[RichardCranium]

Place a notepad or something on the palm of your hand. Now rotate the hand, without rotating your trunk (cue elephant joke). Can you rotate it through 360 degrees? 720? Even more?

I can do it an infinite number of times.

It is the old 'tray of glasses on the flat of the hand' waiter's trick. By rotating the hand about the wrist, the plate can be rotated through 360°; conversely, one can hold one's hand still and rotate one's body around the hand, the only hard bit being keeping the tray steady on the vertical axis.

[TheFaQQer]

Head and foot both "work" in that they go spazzy when I try it.

MrsF thinks it's incredibly funny to watch, as she can write her name whilst rotating her foot with no problem. So, which of us is abnormal?

[TimberWolf]

I can do it an infinite number of times.

It is the old 'tray of glasses on the flat of the hand' waiter's trick. By rotating the hand about the wrist, the plate can be rotated through 360°; conversely, one can hold one's hand still and rotate one's body around the hand, the only hard bit being keeping the tray steady on the vertical axis.

You can do it without rotating your body.

[TimberWolf]

About which axis?

Can we use quaternions? I don't want to end up suffering from gimbal lock

Good analogy. If you can't do it in n dimensions, try in n+1 dimensions.