Six flags over texas ticket costs and discounts?

What would be the cheapest way to get my friend in to six flags over texas? I am from Mississippi so i have no idea what kind of local promotions are going on but with my season pass, i got a coupon that gets him in for 'half off one general use admission at the front gate'. also he is 19 so he is charged as an adult. What would be the cheapest way of getting him in? (I don't care if it is online or at the gate but i think my coupon is only good at the gate) Thanks!