Someone who drinks milk un-ironically i.e without cookies, cereal, spicy foods, etc.
Guy 1: Whoah, is that dude over there drinking a massive glass of milk?
Guy 2: Well I guess that means he’s an un-ironic milk drinker
Childish drink that dumbasses drink for “strong bones.”
“Yeah she drinks milk! Gross! I hate milk drinkers.”
A cocksucker.
You really think you're a match for me, milk drinker?