(Why an apostrophe? It's actually an abbreviation of violoncello.)
So what do you do if you're a clever 'cellist with no one to play around with?
(I'm fastidious about an apostrophe yet I wrote a sentence as unstructured as that one? Yeesh!)
You play a rondo with yourself. A creative and original performance. I think the credits sum it up best: "Everything by Ethan Winer". :)
(Thanks to porsupah for the link.)