Whats with the onion craze?

[MeerMonster]

So...on facebook there is this onion craze going about. It says that putting an onion under your bed when you have disease(flu most commonly) the onion will "suck the bacteria away". But, an onion can't magically vacuum a virus away. And I keep thinking...who made this up? I just had to comment on my friend's status because someone told her to put an onion under her bed. Because it will some how take the flu away. And she also made the mistake of thinking the flu is made of bacteria. Whats your opinion on this(the onion under your bed) and why is it so popular?