happy as a pig in shit

Adjective

Ireland UK idiomatic vulgar

(chiefly UK and Ireland, idiomatic, vulgar, simile) Extremely happy; obviously satisfied and carefree.

Japanese Meaning

非常に幸せで、明らかに満足し、心配事もなくのびのびとした状態であること。 / 非常に陽気で、幸福感にあふれている様子を表す比喩表現。

When she found out she'd gotten the promotion, she was happy as a pig in shit.

彼女が昇進したと分かったとき、彼女はこの上なく幸せだった。

Sense（1）

(chiefly UK and Ireland, idiomatic, vulgar, simile) Extremely happy; obviously satisfied and carefree.