Why "Four Frogs"?

It started when we were first married and Caspian decided to catch and eat flies like a frog would. He became the first frog...then I became a frog and though he resisted David became one too. So now in our house instead of 'dear', 'sweetheart' or 'honey'...we're frogs. Naturally when Samuel joined us last March he became a frog as well.