“At an evening party, Mozart bet a case of champagne that Haydn could not play at sight a piece he had composed that afternoon. Haydn accepted the bet and proceeded to play it on harpsichord only to stop short after first few bars. It was impossible to continue because the composition required him to simultaneously strike notes at two ends of the keyboard and a note in the very center. Haydn exclaimed, ‘Nobody can play this with only two hands.’
‘I can,’ Mozart said, and took his place at the keyboard. When he reached that problematic portion of his piece, Mozart bent forward and struck the central note with his nose.
Haydn conceded saying: ‘With a nose like yours, it becomes easier.'”
–E. Van de Velde, Anecdotes Musicales; N. Slonimsky, Slonimsky’s Book