I can never remember how it goes, and neither can you. So here, I've worked it out again and I'll write it down here for all our benefits:
The great thing about a Gray Code is that, for each transition, only one of the bits changes. This makes it ideal for those situation where you could be sampling the data right when the transition occurs. In such a situation you could (due to alignment errors, propagation delay, aliasing, or other reasons) get a false reading if you were using normal binary representation.
A big fan blowing you at 120(ish) miles per hour suspending you in a column of air and allowing you to do aeronautical tricks (in theory).
Naturally, on your first go you don't really do much other than try stay level and not hit the walls. second attempt was a little better, I was able to steer myself a little and increase/decrease my drag by changing body shape a little.
After two rides I was aching in my shoulders and back, and the next day I was stiff too! When I say two 'rides' I should add that a ride only lasts ONE MINUTE! Quite a work-out!