A keg that has been tapped for atleast a week.
"Dude this zambie yeg tastes like shit"
"Bro were running out of beeh, bust out the zambie yeg from last weekend and feed it to those fuckin zambies"
"We got 2 new kegs and 1 zambie yeg from last weekend"
"When the clock strikes 2 am bust out the zambie yeg and feed it the freshman"