English

Noun

head down, bum up ‎(uncountable)

1. A figurative bodily position adopted when working hard at some task, either physical or mental. (Head down may well be literal, but bum up is figurative.)

   2007: Hadn't heard a thing. Hard at work, head down, bum up. — Gold Coast Bulletin, Call of sea sirens, 6 April 2007

Synonyms

• hard at work
• nose to the grindstone