Wiktionary
happy as a pig in shit
a. (context chiefly UK and Ireland idiomatic vulgar English) Extremely happy; obviously satisfy and carefree. alt. (context chiefly UK and Ireland idiomatic vulgar English) Extremely happy; obviously satisfy and carefree.
Usage examples of "happy as a pig in shit".
Because I'm the sort of person who's happy as a pig in shit just because he's got a mobile phone?
At first I was as happy as a pig in shit with Frank, and Lulubelle was as happy as a pig in shit with Lucy at first.
Made WCS management happy as a pig in shit to get all that publicity, Teddy.
Listen, by your own admission, you were as happy as a pig in shit when you left Portland with your U-Haul.
Engineer Bob sat in the cab, pulling the whistle-cord and looking as happy as a pig in shit.