Ok! First we've got to paint the full picture before we can get the complete significance of the quote:

It's been months since the Battle of Waterloo. Napoleon Bonaparte is being led down to the docks under full military escort to the ship that will carry him and his small entourage into exile. The great general's hands are bound in shackles, his resplendent uniform is tattered and soiled, and the epaulets signifying his high status have been torn from the shoulders. There is a crowd lining the sides of the quay, some mourning the loss of their leader, but most are screaming derisively and throwing bits of filth and garbage at this symbol of the French counter-revoution.

BUT, if we step a bit closer, we can see that Napoleon is laughing hysterically and whispering to his chief of staff with glee, "I spit on their exile! HEE HEE HEE I've hidden a kazoo in my boot!"