Key for Nosebleeds

Q. I read with some amusement about using a key to stop nosebleeds. It really does work!
I am from England and my Dad and I used to get severe nosebleeds. My Mom used to use a key on the back of my neck. It always worked, but the key was about 8″ long and very heavy. It was the original latchkey we used on our back door. The idea was that the shock of a heavy cold key would stop the nosebleed.
A. Thank you for sharing your memories. When we first heard about this, a bunch of keys was suggested, but anything cold–like a butter knife kept in the freezer or a cold washcloth–seems to work.