 In "The Stick of Truth", however, it is revealed that the methamphetamine that Tweek's parents slip into his coffee is the true cause of his paranoia, shakes, and addiction to their coffee.As a result, Tweek is constantly shaking or twitching and is always depicted with spiky, disheveled blond hair and a poorly buttoned shirt.He seems unaware of this as he begs for coffee and has offered coffee to other kids.