On my boat I call myself the captain and my wife calls me Captain Dumbass. Occasionally, I live up to the name...like the time I spilled my coffee into the open fuel fill, or the day I managed to set a hook into my thumb and out my thumbnail. Alas, these are not the dumbest things that ever happened aboard a boat; remember these moronic moves, and make sure you never do them.
 Bite fishing line with your teeth. This created a groove in one of my teeth, which turned into a crack, which turned into a painful visit to the dentist.
 Run a finger across the blade of a knife or butterfish chopper to see if it needs sharpening. My neighbor did this, informed me that the blade was extremely sharp, then bled on my once-clean deck for hours.
 Look through binoculars in a rough sea and ignore queasy feelings, unless you plan to enter a vomiting competition.
 Tie off a mako on the side of the boat and drag it home. I know a guy-coincidentally he owns a Mako-who has no gel coat on his port hullside thanks to the microscopic teeth in a mako shark's skin. (Tail-rope it and drag it behind you instead.)
 Pull the livewell drain while there are small live baits swimming around in there. One's sure to get stuck in the drain line, and you'll smell it for the rest of the season.