im not sure there are codes for park tickets, ive only heard of codes for room discounts-and the only discounts for park tickets i know of are from mousesavers and if you buy them early through the disney website
park tickets really aren't discounted like that. Disney tickets are always a set price. You can get them a bit cheaper through a non disney place (like undercovertourist, some tickets with aaa, etc). Or sometimes there will be a package deal that includes room and tickets that depending on how you look at it, you could figure that as a savings on tickets. But, the tickets themselves through disney, the only discount is the advance purchase price...and you can do that whenever, no special code.