1. Someone who cant go one day (or one hour) without drinking a diet coke.
2. Someone who goes to the bathroom frequently as a result of drinking too much diet coke.
3. A person who is skinny because they use diet coke as a way to feel full, instead of eating food.
"You drank that whole pack of diet coke already?! Its only been in the fridge for one day! You are such a diet coke head!"
-She is always running off to the bathroom.
-Yeah shes such a diet coke head.