A tradition that Pi Kappa Alpha (PIKE) does to haze their new pledges. It consists of making each pledge try to drink a gallon of milk within an hour of arriving at the house, always ending in vomiting by the new pledges.
This is also a reference to PIKE's love of sucking dick.
Jeff "Yeah, I just bought 50 gallons of milk for the milk chug tonight for the pledges."
Chris "I hope they give us head right after they throw up!"