I remember being in 3rd grade and having my music teacher give us all recorders to take home and practice some songs on. (Fun fact -- I can still bust out "Mary Had A Little Lamb" on one, and could probably figure out "Hot Cross Buns" if you REALLY wanted a show)
Apparently, a few California schools did the same thing and handed out a bunch of flutes and recorders. Sounds innocent enough, right? It was -- until it was discovered that a traveling music teacher that was distributing the instruments, had contaminated some of them with his own bodily fluids.
And yes, it's probably the disgusting bodily fluid you're thinking of, which is ridiculously messed up and disgusting. More info below.