Green’s Dictionary of Slang

Ralph n.

[echoic of the noise of vomiting]

[1950s+] (US/Aus.) used in phrs. pertaining to vomiting.

In phrases

call (for) Ralph (v.)

[1960s+] to vomit.

cry Ralph (v.) (also call Ralph, cry Ruth)

[1960s+] to vomit.