clams

Busy day at work today. I'm completely wiped out, but happy as a clam :) Where did that expression come from anyway? Are clams really happier than any other thing? And if so, why? I'd like to know just so I can always be as happy as they are, provided that they're actually happy most of the time. Maybe google knows. Query of choice for tomorrow: clam I should pick a new one every day, perhaps I'd learn something useful.