(as) happy as a clam in butter sauce American simile
Very happy and satisfied
Look at him! He is happy as a clam in butter sauce.
The students were as happy as clams when they knew their teacher will not give them homework.
To make someone feel more confident or happy, especially when they thought that they can't achieve what they want
Happy or cheerful; in a good mood
To smile broadly
The image of the opening clam is very smiling. The phrase derived from the original term 'as happy as a clam at high water'. When the tide is higher, the clams can escape attention from hunters. This expression came from the Northeastern states of the United States in the early 19th century.