Conk/conk out

Conk is British slang for nose, especially a large one, and is first attested from 1812. The origin is not known, but the OED says it probably derives from the word 'conch' meaning a large seashell. 'Conk out' means to fail or give out, as in a car engine ‘conking out’ and dates in this sense from the early 20th century. Some sources claim it comes from the children's game of conkers, in which losers are 'conked' out, but this remains uncertain. See also Conkers.