A person, or persons that look like they would be able to buy a minor some alchohol. ususally found inside of walmart, or out in the parking lot.
Nate: Hey man you want to go to walmart to look for some potential drifters?
Jesse: Ya sure man, what are drifters?
Nate: someone to buy you alch.
Nate: Lets go hunt down some drifters for alch
Jesse: Sounds good man, lets get messed up