When you do something but don't give it your all, always resulting in whatever your doing turning out poorly or incorrectly. Doing things Half-Assed is more than just an act, it's a way of life for most Americans.
Mr.Schoene: Your a smart kid, I don't understand how you're failing so many classes. Jenny: It's because he does a Half-Assed job at everthing he does. Edgar: Well sorry if you don't like my way of life, after all , Half-Assed is the way i was raised.