Hooning down Rhayader Golf Links (quite a well-known section of track in Mid Wales, near Elan Valley) on my Specialized Supercross, and dabbing the back brake around a long sweeping right hand corner to get the back wheel to break loose, and then steering ever so slightly in the direction of the slide to keep the bike upright, while still having 2 feet on the pedals...
That was a memorable one for me. Made me look a much better rider than I actually was!