If you are thinking about the piano-playing performance, that is probably more farce than fact. I looked it up, watched it, and the performers' private areas are blocked from view by the piano. Which is not a real piano, either, as it is expanded at will to accommodate two more "players," and the pitch of the keys does not seem to conform to the normal playing order of the keyboard. Here is one version of the performance: https://www.youtube.com/watch?v=oua0Puihrkc
If you are thinking about the piano-playing performance, that is probably more farce than fact. I looked it up, watched it, and the performers' private areas are blocked from view by the piano. Which is not a real piano, either, as it is expanded at will to accommodate two more "players," and the pitch of the keys does not seem to conform to the normal playing order of the keyboard. Here is one version of the performance: https://www.youtube.com/watch?v=oua0Puihrkc