cloud nine
noun
1
a condition of perfect happiness, euphoria. Probably derives as a variation of CLOUD SEVEN; possibly from US weather forecasting terminology which divides clouds into nine types, the highest being number nine; or, less likely, a spiritual possibility: of the ten names for Buddha, the ninth is 'enlightened one'. It is probable that the US radio adventure series Johnny Dollar, 1949–62, popularised the term's usage US, 1935.
2
MDMA, the recreational drug best known as ecstasy. From the blissed-out state UK, 2003.
3
crack cocaine US, 1994