I'll probably play... Liszt tarantella (the one in g-minor, with all the repeded notes), because I will first learn it, the right way, then i'll lean how to play it up-side-down, and beak both my arms while my grand piano falls down on my head.
Or it might be a brahms exercise. Because they're only pretty hard, I will get upset when I can't play one of them, and I will jump of a roof.
It might aswell be the Dante sonata. Since you get very tired by playing it, I will play it, and then get so tired that i finali fall aslepp at the piano, and go to hell (because of all the tritonus and cromatic scales)