Went sailing with a friend last night. I had little sailing experience when I purchased my O'Day 25 this season, and he helped me motor the boat 40 miles to it's new home, so I thought I should try to get him out sailing once I became comfortable with the boat. He claimed to have taken sailing instruction and had crewed in some races. We were sailing close hauled and I wanted to change head sails, so I steered into the wind and turned over the tiller. My friend decides to turn downwind and let out the main sheet once he has the helm. I step on the head sail and am barely prevented from going overboard by the lifeline at the same time he has an accidental gybe and takes the boom in the forehead.Moral of the story - always wear a PFD, and don't take anyone's word that they know what they're doing.