It's bad to be overconfident in your abilities.
Sam's friend Bill invites him to go rock climbing even though he has never done it before.
Sam wants to respond to Bill's invitation.
Sam tells Bill he doesn't know how to rock climb and declines the invitation, thanking Bill for the offer.
Sam agrees to go rock climbing with Bill.
Sam stays home and remains uninjured.
Sam slips and falls due to his inexperience and is injured.