1. Acting senselessly in situations that typically require only a small dosage of practical knowledge.
2. Lacking common sense, but typically still intelligent.
Common senseless moments are often accompanied by either personal injury or a financial blow, and they almost always involve extreme mortification.
Ex. The most common senseless moment I’ve ever had was when I went to that bathroom in the woods and wiped with a poison ivy leaf. Ouch.
Ex. How is it possible that my sister goes to Harvard and yet she still manages to run out of gas at least once a week. She is so common senseless!