I'm not going to pay a post-tailgate invoice
Why are you refusing to pay? Do you know these people?
Not at all. They are not my friends, they are just some people I barely know.
Even though you barely know anyone at a post tailgate, you should still pay the invoice for it. You are expected to pay all debts that you have.
Well I don't feel like I need to do that!
You agreed to using the services so you need to pay the debt. You can make up what every fantastical scenarios toy want but it doesn't matter. If you eat the food and drink the beer you need to pay up.