This reminds me of a boating story from last summer. The water pump on our 50hp outboard was acting up. To get to it, you need to remove the lower unit of the motor.
The Factory Service Manual (all 400 pages of it!) was vague on putting it back together. I got the new water pump impeller and housing back in just fine, but there is a shift-linkage that needs to be put rejoined as you're reinstalling the lower unit. What the manual DIDN'T say is how to join that linkage "correctly".
I get the motor all put together, and run the boat down to the marina to give it a test run. It was a quiet day on the river, so I slid the boat off the trailer, beached it, and parked the truck.
When I came back to the beached boat, I put the key in the ignition and gave it a few cranks. It didn't fire up, so I added "some" throttle and tried again........
In an instant the motor sprung to life (at about half of it's 8K redline) and launched itself about 10' onto the beach!
Luckily I had the forethought to put the wrist-safety-tether on because as soon as the boat got about 3 feet away the tether broke away and shut down the motor.
I imagine the look my my face was pretty funny as I'm standing there with a red wrist tether dangling from my left arm with a "WTH???" look on my face and a boat beached HARD...