Happy-go-fuck-you

A person who outwardly appears happy and nice but acts condescending and passive aggressively.

Our waiter looked so nice at first but he had a real happy-go-fuck-you attitude.

What’s wrong with her? She seemed so cool at first but then her happy-go-fuck-you personality really came out.

Have you guys seen Randy lately? Ever since he came back from that two-year trip to London he’s changed into a happy-go-fuck-you kinda guy.

Happy To You!

An all-purpose spoken phrase to express sarcastic joy towards another person's lack of accomplishments.

Dean: "Hey Brent! I got a participation award for best participant!"
Brent: "Ooohhh. Happy to you!"

if you're happy and you know it clap your hands

Describes the action of a very happy person.

Also part of a song.

If you're happy and you know it clap your hands
*clap* *clap*