Just go take a bunch of stuff to the counter tell them you forgot your money in the car and then just leave. Dirty bastages!!
I know you're probably not serious, but ... with all the posts about pooping in sinks and what not ....
Just remember that a lot of ordinary people probably work at these gas stations, and a lot of them probably aren't Hawk fans (or any type of fan at all). I don't want to make a "regular employee" do something annoying or gross just because their bosses did something like this.
If you want to react, just don't give them any business. That will be enough.