Man, in all my years I've had quite a lot of pucker factor moments. This one was the worst though:
Out in Colorado a few years ago, my brother and I were running east on Rt.160 towards Monte Vista in the rain at nightime. We were under the speed limit due to the rain but it was warm and not too bad, when suddenly our bikes just completely lost all traction. It was like we were floating on the road, both tires felt like they were simply gliding all over the pavement for a span of like ten seconds, and then just as sudden as it started BAM they grabbed again and we were fine.
It scared the living crap out of us! Lucky it was a straight section of 160 because if it had been a curve we would have gone down for certain. In 34+ years of riding we'd never felt anything even remotely like that before, and we've both experienced hyrdroplaning and riding over fluids plenty of times. We actually pulled over and walked back to see what the hell was on the road to cause that, but there literally wasn't anything odd or unusual, and the road felt fine to us. Ten seconds of utter terror and horror. To this day we don't know what happened, it must have just been some freak hydroplaning event or something.