When is Free Pizza Not really Free

Tonight I'm going to the local Harley dealer for the 1 yr anniversary of the new owner taking over. There is going to be free pizza & tons of discounts. Now this Pizza isn't likely to be free because people are gonna spend a shit ton on stuff because its on sale, not me I'm going for free pizza & that's all, what if someone had a promotion & everyone just came, ate some pizza & left? That would be a glorious day