Defenestration

Noun - The action of throwing someone out of a window. (From the latin fenestra - window). Source: The Oxford English Dictionary.

The old 'What does defenestration mean?' prank had gone too far this time...

I like this word as it demonstrates the fact that the action must have occurred with sufficient frequency that someone must have felt that there was a need for a specific word to describe it.
Its Latin root suggests that it is something which has been happening since at least Roman times and I believe this can only be a good thing as it has lead to the creation of such an interesting and amusing word.
Note that the word only applies to throwing people out of windows: there is actually no word (that I can think of) for throwing inanimate objects or animals through windows.
Also, I would perhaps alter the Oxford definition to: 'the action or art of throwing someone out of a window' because if you are going to do something, you may as well do it with style.

Usage: "Rapunzel, Rapunzel, let down your hair. But take care not to defenestrate yourself."