Definition of Mike-Mike in English:

Mike-Mike

(also mike-mike)

Pronunciation /ˌmʌɪkˈmʌɪk/

noun

military slang US
  • Especially in the war in Vietnam: a weapon, or ammunition, the calibre of which is measured in millimetres; a millimetre (chiefly attributive).

Origin

1960s; earliest use found in Esquire Magazine. From Mike + Mike, after mm.