Go here to become Skittles Facebook Fan and then click on the tab that says "Coupon the Rainbow". Fill out your info and click "get coupon" to print of your BOGO coupon.
For Starburst, Go here and become a Facebook Fan. Then click on the coupon tab and fill out your info. Click "get coupon" and you are set. Your BOGO coupon will print. (Thanks Hip2Save!)