The act of throwing up so violently the person is yelling at the same time.

Cocaine.

To not only throw up, but to do it with a terrible yelling sound. If done properly yarfing will cause veins to pop out and eyes to water.

To throw up

To violently throw-up

yarf is a slightly negitive greating in the vulpin language, usually used to in a wat to imply one isn't feeling well

A combination of yakking and barfing.