Be like the cat that got the cream

Be like the cat that got the cream

Meaning:

(about a person) To be pleased with his/her ability or what he/she has done.

If you are like the cat that got the cream, you are very happy because you are happy about or satisfied with your own talent, accomplishment, or what has happened to you.
People also say, "You look like the cat that ate the canary."

Example:

At our high school reunion last week, Sue grinned like the cat that got the cream and told us about her success story.

She got 100% on her final exam yesterday. She looked like the cat that got the cream.