Beethoven was a musician for the Electoral court and chapel in Bonn. Franz Wegeler, a friend of of Beethoven’s, recounted an incident where the young Beethoven was to accompany a singer, Ferdinand Heller, in a church service. Heller prided himself on being able to sing in tune, no matter how complicated the accompaniment. Beethoven asked Heller if he could alter the accompaniment. However, Heller became confused, and couldn’t gain a sense of key in the closing cadence. Heller complained to the Elector, who apparently smiled at the temperament of his artists, and gently suggested Beethoven return to simpler accompaniments. Beethoven’s biographer, Anton Schindler stated that Beethoven remembered the incident and that Beethoven “was most graciously reproached and forbidden to play any more such clever practical jokes in the future.”

Source:  Marek, George (1969) Beethoven: Biography of Genius. London: William Kimber, p.51