Wolfgang Mozart sure was a goofball.
The composer had a fantastic, sometimes childish sense of humor that often got him into a lot of trouble with his patrons.
In any case, Mozart knew how to have a little fun while composing some of music's greatest masterpieces. A good example is this selection taken from the finale of Don Giovanni.
In the scene, Giovanni is waiting for the statue of the Commendatore to arrive for dinner. As he waits with his servant Leporello, he orders his musicians to play music for him.
Mozart then throws a curve ball to his audience when the on-stage band plays an aria from another of his great hits, The Marriage of Figaro!
That opera had only premiered a year before Don Giovanni, but it was still an immensely popular, albeit controversial, hit. Leporello seals the joke by saying, "I know this piece far too well!"