On cloud nine
Definition 1 of 1
Pro Tip 1/3Expressing Euphoria
Use 'on cloud nine' to express a high level of joy, often unexpectedly or in a rare occasion. 
She was on cloud nine when she got the promotion.
Pro Tip 2/3Informal Context
This phrase is informal, so it's best used in casual conversation, not in formal writing or speeches. 
I'm on cloud nine because my best friend is coming to visit!
Pro Tip 3/3Figurative Expression
Remember, 'on cloud nine' is figurative and doesn't refer to an actual physical location or state. 
After winning the lottery, they were suddenly on cloud nine.