The act in which one cosumes alchohol prior to attending an event at which alcholic beverages may or may not be served. Often popular with university or college students who can't afford to buy to many drinks at a bar or high school kids who plan to attend events such as dances.
Are you going to Paddy Connolly's tonite? Yea but we are going to pre-drink at Dave's.
Before Johnny went to the dance he pre-drank a mickey at Paul's house.