crackers

See cracker +‎ -ers. The South African sense derive their name from their sound and their status as a plurale tantum by association with "trousers". The adjectival sense derives from British naval expressions referring to firecrackers in one's head, originally as "he's got the crackers" and then "he's gone crackers" before the present "he is crackers".

crackers

1. plural of cracker
2. (South Africa, only plural) A kind of noisy leather pants or trousers.
   • 1849, E.E. Napier, Excursions in Southern Africa, Vol. II, p. 13:

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

crackers (comparative more crackers, superlative most crackers)

1. (Britain colloquial) Crazy, insane.

• See also Thesaurus:insane

crackers

1. Third-person singular simple present indicative form of cracker