Snoopy Jaws Harp/Jews Harp
A cool jaws harp, like Snoopy plays in the old Peanuts TV show. Makes a really cool "boingy boingy" sound that you can easily learn.
To play it, you stick it in your mouth and pluck it with your finger.
The Snoopy harp is actually a really old instrument, patterned after the original American Jaw Harp. It is also called a mouth harp, jaw harp, Ozark harp, gewgaw, Jews harp, or juice harp. It's unclear if the term "juice harp" was a misheard pronunciation of "Jews harp" or perhaps it has to do with the mouth juice that this instrument creates!
It classified as a lamellophone instrument, which means that it is a "plucked idiophone".
Whatever is is and whatever the history, it's fun, sounds cool and is easy to pick up.