Some of them don’t know. One of my favorite jokes goes like this:

I work in a vacuum cleaner factory. My wife could use a vacuum cleaner, so I decided to take a different part home every day, so that eventually, I could build her a vacuum cleaner at home. But no matter how I assemble the parts I took, I always end up with a submachine gun.

It’s from a German short film on napalm called The Inextinguishable Fire. Very short, worth a watch. Holds up.