Things I've done at least once:

Forgot to put the plug in. (twice)
Left the transom saver connected and damaged prop. (once)
Forgot to lift the trolling motor before taking off. (countless)
Backed my boat in too fast while unhooked and had to swim after it. (once)
Got the the lake and realized that I forgot all of my rods. (once)
Spent 30 minutes trying to figure out why my boat would start and the kill switch was off (once). I was a new boat owner and that was 15 years ago. :o)

I'm sure there are many more, but these are some of the big ones that stick out.

Let's hear y'alls.

When I was 18 i bought my first Boat. Tige Wakeboard boat. Me and My friends anchored in about 30' of water to just chill for a bit. Well someone forgot to pull up the anchor when we took off. Thanks God nothing happened! I didn't remember it was out until about 200 yards down the lake!!!

Forgot to put the plug in (first time I took my first boat out DOH!!)

Was night fishing with my Bro-inlaw and had 4 rod & reels rigged in a small boat. Was chunkin a crank bait into the mouth of a feeder creek with the boat sitting over 40' of water. One of the treble hooks caught the eye of my rod with my prized Team Daiwa reel on it and before I registered what was going on I could barely see my rod & reel slip off the edge of the boat into the abyss.....I can not explain how pissed I was as my Bro-inlaw laughed his A$$ off.

Right before a big fishing trip to Lake Caney (back when it was in its prime) my Bro-in law and I put a new steering cable on the boat and headed out. Got to the lake and realized that the steering was backwards - turn left boat goes right etc. Didnt stop us from having a good trip though. LOL

Forgot plug
Left trolling motor down (more than once)
Left rods on back of boat when driving off (that sucked)
Left boat tied to trailer when launching (once, pretty funny though)

I have ownd a boat for 20+ years so I have a few. Here's what I can remember
1) At the lake and disconnect the trailer to go to the store. Come back from the store and reconnect trailer to launch the boat but forget to latch the hitch. Back down the ramp and trailer, boat and all conme off the truck and launch themselves. Could have been LOTS worse but boat was disconnected fromt the trailer and floated off almost perfectly into the marina dock and was able to easily reconnect the trailer. My bud's had a great laugh, me not so much
2) Had a problem with the front seat pedistal sticking in the connection at the deck. No problem, lets put some "Never Seize" on the damn thing. Next trip out I lean over on the seat and seat, pedistal and me all go into the water. Pretty cold water too
3) Picked boat up from boat stall and forgot to latch the hitch and trailer came loose from the truck. Thank God I had safety chains on and wasn't going fast (once)
3) Left plug out on boat once in each boat I have owned (2 boats)
4) Left plug in the boat at the hotel and it rained HARD. Pretty much flooded the boat up to the seats. When I pulled the plug the water shot out about 30'
5) Lost count how many times I have left the trolling motor down. None recently though

Nate, I think loosing your whole boat/trailer down the ramp will definitely make the top 3 on this thread when it's all said and done, if not 1st place...lol!

Forgot the plug on my first boat ( once)

Forgot to pull the anchor up. The boat would not plane out then I realized the anchor as still in the water. ( happened once)

Forgot the life vests at the house because I took them out to dry and never put them back. ( once )

Forgot the keys ( once )

I forgot about the trolling motor being down and taking off. ( I don't even know how many times )

I bought a bass boat, enough said.

Tried to launch boat when it was still tied down.
Worked on Trolling Motor before a tournament, put it back on exactly backwards to directional arrow. Started fishing near the launch site, I was just trolling in circles and my partner in the back was just fishing away and laughing. The 15 or so waiting to launch got a kick out of that.
Was fishing a secluded cove when I stepped up on the bow and took a leak, all went well until I glanced up in the brush, there was a lady sitting on her horse laughing at me.

Put the trolling motor down at the car wash while washing my boat. When I finished washing the boat I drove to the boat storage...trolling motor still down. The road had ground the skeg on the TM off but it still worked fine.

Jason

sounds like a bad dream.

LOL!

We've all been in too big a hurry and forgot plugs, transom savers etc... here's a few that I'll not soon forget.

Left the plug in and drove 130 miles to Palestine in the pooring rain. We had a nice bath tub boat full of water when we got to the lake lucky we did not blow a tire. The flood ruined the Minn Kota foot pedal variable speed control slider. Did manage to fix it well enough to fish the tournament.

Lauched the boat at Fork and thought my buddies from Temple had pulled the right side transom tie down...nope they thought I did? Sure looks funny when the front of the boat swings 90 deg to the trailer. Not to mention they're all standing at the ramp pointing laughing at your mistake, while you sit in the boat head down.

Had the bright idea to use a 12vt car light dimmer switch for my foot switch on a 12/24vt hand control Motor Guide trolling motor. It worked great on 12vts when I installed it, then the wind got up and I switched to 24 volts. Smoke on the water!

Left my master power switch on and the auto bilge pump float got stuck turning the pump on. Got to the lake to prefish and the start battery is dead as a hammer. We left the jumper cables at home, so we had to take the pickup truck battery out and wait an hour for the alternator to charge the boat battery. It burnt the pump up so we had to change that out too.

Fishing Ray Bob I pushed off on a rotten tree the wind blew us into while netting a fish, of course it broke off and I took the TM hand steering rod with me into the water. I had to jamb a tree limb in the remaining pipe to finish out the tournament day.... soaking wet DOH!

Learning what not to do as a boat owner is humbling, but so much fun when you get it right.

Jumped a chain link fence at 42 years old.