Forget your run-of-the-mill demolition derby (where junker cars smash into each other). In Lind, Washington, they have demolition derby competition with ... combines!
Each June the small town of Lind, with it's one restaurant and one bank, celebrate Lind's weekend complete with BBQs, car races, grain truck races, and the Combine Demolition Derby!!!! Hell, a normal demolition derby is great, let alone massive harvesters crashing into each other at what I can only imagine is high speed.
http://www.gosleepgo.com/go/combine-derby (with embedded Revver video) - Thanks Scott!