I liked this bit Williams said about working with Jeff Bridges:
Something screws up and [Jeff Bridges] says to me: "It's ok. It's a gift. If something screws up, it's a gift. Don't be afraid of it." That forces you to make something special that you didn't plan. You're in that moment and you're forced to deal with it and deal with it together.
He's talking about acting but applies to standup too. A perfect set is the same every time. But when something goes wrong, it's an opportunity to make a unique moment happen. It's you and the audience in it together.
Now I've just got to convince myself that Seamus — the drunk guy in Jersey City last night who kept yelling out to me "Show your tits!" — was NOT an asshole and was actually giving me a gift.