Green’s Dictionary of Slang

s.o.s. n.2

[abbr.; smash on sight or shoot on sight]

(US gang) a contract to murder.

Amer. Patrol Report 26 Dec. 🌐 Milwaukee: Latin Kings member gets 10-year term [...] The Kings issued an ‘SOS’ – which stood for either ‘Smash On Sight’ or ‘Shoot on Sight’ – for Garza, and that order was in effect when Espada saw Garza in a National Ave. barbershop in February 1997.