A song you can play on an instrument. Sadly, I took years of piano and years of clarinet lessons and haven't really retained much. I own a guitar and my boyfriend can play it better than me, and he's never had any music lessons. Alas, I can play When The Saints Go Marching In on the piano and the very beginners version of it. I sound about as good as the person in the video.
Click the link for the most dull version of When The Saints Go Marching In ever played.