Lads! Let's round up the old Bentley, polish her up a bit, and take her mudding on a slippy trial in the middle of the woods! Right ho!
I know that real British people nowadays are too busy doing designer drugs to do this kind of thing, but it still strikes this American as the most classically aristocratic sport from fair Albion I'll ever see. I mean, unless some duke comes up with a way to play polo while riding on his servants.
Here's a full explanation of what the hell is going on in this video, showing the VSCC's Hereford Trial. The video above is from 2008, the explanatory video below, 2013.