a means to exaggerate yelling ; next-level yelling ; a parody of an individual becoming so excited that yelling must be followed with vomiting to fully express their excitement ; mostly used in a humorous context as an overly-excited reaction to an unexciting situation or event.

to vomit in a loud, painful, violent, rapid and occasionally tearful manner, i.e. vomiting that requires a great deal of energy.

When barfing so hard it sounds like you're yelling while barfing.