From Harmony Central.

My theory is that missing trem-arms go through some sort of Worm Hole, and end up in "The Box", where the Keeper of The Box looks into your soul, and if he finds that it is pure, he sells you a trem-arm for a couple of bucks.

I still own 3 guitars with their original tremolo arms - what can this mean?

That reminds me of the net meme that went 'round a few years back that finished with the phrase "and who was phone?" But I can't remember the rest or why it was so hugely funny at the time