h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

This actually works. I heard it in 7th grade from my English teacher, who brought an old home remedy book to school. When I've chewed gum (or on a piece of paper, if you don't have any) while my nose was bleeding, it did seem to stop sooner.

Sooner than? - how did you know? Did you use interdimensional communication to find out how long an alternate, non-chewing you bled for?

I find this method does work, but only if you stick the chewing gum up your nose ...

There is a very easy way of stopping a nosebleed, but it's not for the faint-hearted: simply lie on your back. The blood will rush down your throat... at this point it's important that you don't cough, or choke. Other than that... it works for me.