What is Existential Courage?

When you've never ordered at a fast food chain in America on your own and you head up to the cashier to tell him what you want and pay the price then forget about tax and another dollar then you don't hear him over his accent asking if it's to go or for here because you're used to the term "dine in" so you say "huh" three or four times then you finally understand once your cousin speaks up from behind you...so you say for here and then freeze because you're unsure when to say thank you- so the appropriate time lapses and you just walk away wondering if the cashier finds you rude and suddenly you wish you had ate at home instead.