Insult connoting the means by which one swallows semen; an alternative to the term "cum guzzler". Typically used to describe a reserved, conservative individual whose behaviour or personality evokes disgust or indignation.
You: Check out that old bitch in the business suit eyeing us with a look of disapproval.
A sipper is a person who consumes copious amounts of cough syrup otherwise known as "lean", "sizzurp", "syrup", "purple drank", "purp", "barre", "purple jelly", "texas tea" and "Tsikuni" to get a high from the promethazine/codeine. Typically served in a double cupped styrofoam cup with Sprite and crushed ice.
"She's double cupping, she's definitely a sipper!"