1. The condition of someone who's had great sex the night before. Often endured (barely) by coworkers and friends. Always accompanied by a smile nothing will wipe off.
2. Adjective to describe a racecar experiencing severe oversteer or looseness. A loose racecar's back wheels tend to head for the outside of the track in a corner. Hence, the tail is merrily out of control and trying to spin the car out.
1. Bob's girlfriend is back in town. I suppose he'll be tail happy all day long. Makes ya wanna puke, doesn't it?
2. Dale Earnhardt, Jr., is downright tail happy coming out of turn 3. He's gonna slap the wall if he isn't careful.