Not me, but a buddy I was in the raft with:
Going down a shallow gravel drop he digs the down stream oar. It immediately pops straight up, jumps out of the lock, and fires off down stream of us. His first instinct is to jump in and grab the oar. No problem because its super shallow right? Only problem is the boat is going much faster than he can run in the water so the boat runs him over basically as soon as he gets out. Fortunately its summer and we are wet wading. The raft floor makes that grrrunnnnnnuunnnp sounds like when you go over a shallow rock and he pops out the other side. By now we've dropped into the next run, too deep to stand up, so he is just hanging off the side like a wet cat.
I'm doing 2 things: Keeping an eye on my oar and laughing hysterically. Eventually we float up to the oar and I grab it just as we get to the tail out and he gets some footing. I put the oar back in the lock and ask him if he's done fucking around yet because I'd like to go fishing.
Same buddy in the middle of the John Day canyon: Its getting dark so we are stopping to scope camp sights. We pull over at a nice looking spot and get out. Good flat camp spot but its way up a sandy hill. We decide we can do better and get back in the boat. We find only one oar. Apparently when we stopped he shipped the oars a little too hard and one fell out the other side. I had a spare but it was pretty janky. Throw that sucker on and spend the next 15 mins checking back eddies and charging down river hoping to find it still floating. Don't see it and by now its dark so we grab the next camp. Never did see that oar again and now its sibling is my spare.