Last year's endurance downhill at fort william, tried an optimistic line for an overtake and just hammered the rear wheel into a rock- flattened the rim more than the tyre Only about the third ride on that rim too, it took a tube for the rest of the day but was junked. Cost me my 14th run too which would have been a pb, ah well. Oh and it was one of those expensive Eclipse tubes too!
How about best punctures? Innerleithen 2 Days In May enduro, riding the Classic, picked up something spiky and got a slow puncture in the early section, banged on the brakes for a rock garden in the black route, and boom! Tyre spins round rim, rips valve off, straight into rock section at speed of light, luckily I was going fast enough that my crash carried me right over the rocks into a nice soft bit. So what can you do but carry on? Rode (most of) the rest of the black and down the steeps on the classic with the tyre spinning madly on the rim. Wasn't fast but man it felt heroic.