Could someone explain what's "funny" about Transmosify/Transmosifier
in German?

What I think is good about this name is that it explains what it does
(of course not for everyone, but it's not only used in Calvin &
Hobbes, it has also been picked up and used by many others.. I think
there was a Star Trek game for Amiga where you could get one of these,
for example). It's perhaps a bit long, but it could always be
abbreviated to TMF when referred to in context.