No, it's not one of those, but if it's from a bike, it could be a blank cover for an unused connector.It looks similar to plastic guards that fit over electrical connections. I see this all the time on the ends of some non-polarized AC cords.
I have a 1991 that I completely refurbished three years ago. Never saw this part. It does look like a cap for an open two prong connector, maybe from an add-on device?It's off a '91 ST1100. If memory serves, the two parallel slots on the second photo slipped over two blades, and it's a friction fit. Maybe a damper between two pieces (think I might have been swapping the air filter at the time). Bike seems to work fine since, but I'd like to put that wherever it's supposed to be, I'm sure Honda didn't just stick it there for fun.
So, he was really just screwing with you, eh?My Dad thought it was the absolute HEIGHT of hilarity to walk by and toss in an extra machine screw , then wait for me to go ballistic trying to remember where it went.
So, he was really just screwing with you, eh?