Green’s Dictionary of Slang

Ralph n.

[echoic of the noise of vomiting]

(US/Aus.) used in phrs. pertaining to vomiting.

[US]D. Burke Street Talk 2 24: Talk to Ralph/Huey on the big white phone [...] ‘Huey’ is close to the sound that one would make while vomiting.

In phrases

call (for) Ralph (v.)

to vomit.

[US]Eble Campus Sl. Spring 6: toss cookies [...] call Ralph, call Hughie.
‘Savannah’ on Lincoln Park RFC [Internet] Crombie did his 2 time per game ritual of calling for ralph and clearing impurities from his stomach (prior to kick off both halves).
cry Ralph (v.) (also call Ralph, cry Ruth)

to vomit.

[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 70: I’m as crook as Rookwood. I reckon I might have to cry ruth pretty soonish!
[US]Eble Campus Sl. Spring 6: toss cookies [...] call Ralph, call Hughie.
[NZ]McGill Dict. of Kiwi Sl. 95/2: ruth vomit, phr. cry ruth; derived from the sound involved.