There are some players out there who don't actually defend you, they try to intimidate you for an hour on court. They'll press themselves up against you even when the ball is on the other side of the court and with that comes the creepy experience of having their hot breath on your neck and their hands resting on your backside. So you do what comes naturally to you, you'll stick your bum out as much as possible to get away from the Hannibal who happens to be your defender for the next hour.