be (as) happy as a clam (at high tide)

be (as) happy as a clam (at high tide)

To be very joyful and content. Clams are dug at low tide, so a clam at high tide would be able to remain uncaught. Look at your sister out there! She's happy as a clam at high tide now that she's back in the starting lineup again. I know I'll be happy as a clam at high tide once I get this stupid cast off my leg.

See also: clam, happy, high