Josh Miller is a studious and responsible pre-med student entering college as a freshman. His wild, hard-partying roommate Cooper Frederickson, on the other hand, is a spoiled rich kid who never studies and spends his time getting drunk and ogling co-eds. Before long, Cooper's fun-filled lifestyle has corrupted Josh, and both are on the verge of flunking out.
Jane (Anna Faris), a struggling but perpetually stoned actress, has a busy day ahead. She has several important tasks on her list, including buying more marijuana. Even though she already has a good start on the day's planned drug use, she eats her roommate's pot-laced cupcakes and embarks on a series of misadventures all over Los Angeles.