In one of the funniest songs in The Pirates of Penzance, the Pirate King explains that young Frederick, having been born on Leap Day, may have been alive for 21 years — yet, if one goes by birthdays, he’s only 5!   After they sing, they have the following discussion:   Frederic. Upon my word, this is most curious – most absurdly whimsical. Five-and-a-quarter! No one would think it to look at me! Ruth. You are glad now, I’ll be bound, that you spared us. You would never have forgiven yourself when you discovered that you had killed two of your comrades. Frederic. My comrades? King. (rises) I’m afraid you…