Like the harmonica, the slide whistle is one instrument you need no skill to play—you just blow in one end, and slide the other in and out. Unfortunately, that means that handing out a bunch of these adorable Wet My Whistle musical straws at your next get-together will result in a room full of amateur musicians trying (and failing) to play a tune.
Sliding the whistle in and out of a beverage changes the amount of empty space inside, which in turn produces different notes when played. And in case you were wondering, yes, they do work as a regular straw, as long as you cover that air hole with your finger as you suck. [Fred & Friends]