Green’s Dictionary of Slang

earl v.

[echoic]

(US) to vomit.

[US]Eble Campus Sl. Sept.
[US]Eble Sl. and Sociability 40: Onomatopoeia, or echoism or imitation of sound, accounts for many slang terms, including these for ‘vomit’ – barf, buick, earl, ralph, and yuke.