Celebrity Attractions brings 'Sister's Christmas Catechism' to Oklahoma City.

“I use a different technique to choose each character,” Richards said. “For Joseph, I look for a Jewish carpenter. Sister has a theory though that Jesus was the last Jewish carpenter. I like to ask women in the audience why they think they deserve to play Mary.

“The classic response is ‘I'm a virgin.' I remember one woman who said she'd like to be a virgin again. One of the most unexpected volunteers was a head nun who had to be 87 years old. You can't anticipate moments like that.”

Richards says she calls on her years working in improv to help her through situations when audience members try to trip her up. It's not too hard either to guess who tends to be the most outrageous or ill-behaved patrons? The Catholics, of course.

“Anytime you're talking to an audience, you never know what's going to happen,” Richards said. “It's off to the races — you drive the car and they let you know what direction you're going to go in. Every night something different happens and the audience will always remember that.

“You can't write those moments and you can't recreate those moments. It's never mean spirited because it's always done in fun. And if something funny is going on, I'm laughing right along with them. The interesting thing about this show is that you could come five nights in a row and never see the same show twice.”