Dude, at this point id really like to say you need to spend some time reading up about your bike rather than asking questions. Its the whole "teach a man to fish he eats forever give him fish he eats for a day" thing.
But you would need to change the number of teeth on either your rear cog or crank chain ring by replacing them with a different one. Seriously though gearing isnt going to help you skid. You just gotta stop being a puss about it. Im 150lbs after dinner and can skid 15 feet or more depending on my speed. Check the tires, and the surface your trying to skid on. AKA sidewalk is easier than pavement but blacktop is best. Also slicks are going to be easier to skid with than a commuting tire.