Definition of blues and twos in English:

blues and twos

noun

British
informal
  • 1The flashing lights and siren used on a police car or other emergency vehicle when responding to an incident. Also later "on (also under) blues and twos".

  • 2The emergency services (frequently the police).

Origin

1980s; earliest use found in Autocar. From the plural of blue + the plural of two, with reference to the blue flashing lights and (typically) two-tone siren used on an emergency vehicle.

Pronunciation

blues and twos

/ˌbluːz ən(d) ˈtuːz/