The complete opposite of a designated driver. A person who always get's smashed and drinks alcohol like it's nothing. May possibly drive you to the club but not back home. If it's you and the designated drinker expect to only have one drink because your driving home unless you want a smashed car.
"Fuck a wristband, lets all do a keg stand. I'm like cheech and chong hittin up the beer bong. When the cops show up they're gonna get the finger and I don't give a fuck. Cause I'm the designated drinker."