Your centre of gravity is the point around which all of your weight is centred. It is also the point around which we maintain our balance. One of the problems that babies have when they are learning to walk is learning to keep their centre of gravity over their feet. Women's centre of gravity tends to be in the hip-area and men's centre of gravity is higher, usually in the upper torso. So you would be more likely to get the CD if you are a woman.
All objects have a centre of gravity.
For instance, you can find a ruler's centre of gravity by finding the point at which it will balance on a fingertip. The centre of gravity is very important in engineering because it tells engineers how objects can be balanced or how they might become unbalanced.