The C/T Antigravity Gyro
This marvel of modern sciencey-ness is based on the twin principles:
A dropped Cat will always land on its feet.
A piece of buttered toast, when dropped from any height, will always land butter-side down.
Therefore: If we strap a piece of buttered toast1) on to the back of a cat, and drop the resulting assembly, instead of hitting the ground it will begin to rotate at high speed and will hover some distance above the ground2)
This principle had, for reasons yet unexplained, remained a theoretical construct, without even the most cursory laboratory research attempted to prove or disprove it. EGfBT, however has recently constructed at least two vehicles based on these sound physical principles.