My most memorable grounding was when I was in highschool - I spent my summers working at a Marina on the Magothy (one river north of Annapolis) and crewed on somebody's boat every Wednesday for the Gibson Island races. This particular Wednesday I was on a Cal 29 who's owner was/is a great racer. We were running late and hurrying to get to the starting area, the owner was below with his charts and the other crewman, an Air Force officer, was at the helm. I was hanking on the jib, resting my butt on the bow rail.
I was only sort of paying attention when I heard the zoomie at the tiller muttering "red right, returning...we're returning to the Bay so I should go to the right...". It took a second before it dawned on me what he said - I looked over my shoulder to see that we were in fact headed to the right of a green marker, generally heading toward a crowd of people having dinner in a gazebo in front of their condos. I stood up to just as we hit hard, my momentum carrying me over the bow rail. It must have been a good back flip because I could hear the dinner crowd arguing over whether the judges should have given me an 8 or a 9. At the same time down below, the boat's owner fell into his settee shattering it.
The water where I landed was only waist deep so I between revving reverse and me pushing the boat came right off, me swimming after it as it raced in reverse. The owner was now on deck at the helm and he sent the zoomie to help me back aboard. I was able to grab the toe rail and swing one leg up which he promptly grabbed causing me to lose hold of the toe rail so now I'm hanging upside down, facing away from the boat with my head bouncing on the water. Zoomie then grabbed the cuff of my shorts to pull me aboard but all that did was cause them to pull down to my ankles - I distinctly remember being able to hear laughter from the gazebo. Zoomie dropped me and I managed to lose my shorts before they finally got me back aboard.
We did get to the race on time and for the whole race all I had to wear was my T-shirt tied around my waist. I do remember that we won.