A person who buys everything without thinking about it, or because she/he simply needs to buy something to be happy.
A company's best friend
Consumerzombie: "I am a big fan of DLC for games, these are awesome! I bought every single DLC to date, because these make games great"
Smart Person: "Damn you are a consumer-zombie, buying this cheap crap without thinking. DLCs are just the new way to milk money from dumb people like you.."