Definition of "crackers"

Sheepskin trousers—which, from the sound they make at every movement of the wearer, are called ‘crackers’.

1849, E.E. Napier, Excursions in Southern Africa, volume II, page 13

He acknowledges that it must seem "a crackers thing to say", but given the substantial progress which has been made in other areas of the business, his optimism isn't without foundation.

2021 May 5, Graeme Pickering, “Managing Metro's morphosis”, in RAIL, number 930, page 52

Dominic Cummings, Boris Johnson’s former chief adviser, told the online magazine UnHerd in May that Truss was “as close to properly crackers as anybody I have met in parliament” and would be an “even worse” prime minister than Johnson.

2022 July 30, Dominic Cummings, quotee, “‘Ambition greater than ability’: Liz Truss’s rise from teen Lib Dem to would-be PM”, in The Guardian‎