Over the moon

The image traces back to the old English nursery rhyme "Hey Diddle Diddle," in which a cow famously jumps over the moon, and general figurative use meaning "delighted" is recorded in English from the 19th century, well before its most famous modern association. That association came from British football culture: from the 1970s onward, TV pundits and players used "over the moon" (paired with its gloomy opposite, "sick as a parrot") so relentlessly in post-match interviews that both phrases became a running joke about footballing cliche, even though neither one originated in football at all.