That's why they're fun. I always got the impression they're making fun of the usual management euphemisms. No one is under any illusion about what an "energetic engine failure" or "rapid unscheduled disassembly" is.

Building these things is incredible amounts of time, money, and, most importantly, effort and labor.

Doing something to keep spirits up when months of hard labor explodes in a few milliseconds is practically required.

There are a lot of hands at very hard work here in the Texas heat. It’s easy to abstract away whilst sitting in an Aeron with a text editor.

Rocket engineers have a sense of humor

They (SpaceX) also use RUD (rapid unscheduled disassembly) which is fun.

I mean, it makes sense. Rocket engines are machines for controlling the release of enormous amounts of stored energy. So, many of the failure modes can be broadly categorized as either "not enough energy" or "too much energy in the wrong place".