There's something intrinsically funny about that word. I think part of it is that it sounds like of like "masturbation", and part of it is that it's so unusually specific - why do we need a word for throwing someone out a window?
Well, "defenestration" is a sort of inflexion of a common word (in Latin or German, which was a common language in Prague in 1618).
Wikipedia has quite a few examples, so having a specific word might be useful in the end: https://en.wikipedia.org/wiki/Defenestration