Where Did the Phrase "Pleased as Punch" Come From?

Why are we sometimes pleased as Punch? How happy can a tropical fruit drink be?
The pleased Punch in question is not a drink, but a puppet. The traditional, ages-old Punch and Judy puppet shows feature the married couple battling each other with clubs.
In the original story line, hunchbacked, hook-nosed Punch eventually beats not only his wife to death, but also his infant child, along with a policeman, a doctor, a lawyer and the Devil. Punch is deliciously self-satisfied with his sadism, constantly uttering his catchphrase: “That’s the way to do it!” Punch’s strutting pride in his awful deeds is what led to the coining of the phrase (in the early 1800s) of being “pleased as Punch.”