Dundas, reached in his native Australia before a lengthy U.S. tour, has been performing as a duo with Collins since 1990. Together they've crafted at least three acclaimed long-running performance pieces, including Thwak, which has been an international hit since its launch in 1999. For Thwak, the pair draws on all sorts of inspirations, combining broad, physical comedy and some crazed voice work.
"Repeatedly we get people saying, 'Man, I've never seen anything like this,'" Dundas says. "That's great. People are always discovering us for the first time. And unless you've seen us before, you don't know what to expect."
That's especially true for St. Louis audiences, who'll be treated to the Umbilicals for the first time. It'll be a treat for Dundas and Collins as well because St. Louis is the kickoff city for their American tour.
"There's more energy and a few nerves on the first night," says Dundas, "and that's part of the excitement for us. We'll be touring the States all through this year, and you guys are the first."
Dundas says the duo's act does have subtle differences when played for stateside fans.
"It's interesting," Dundas says. "We basically have kind of modified what we do for American audiences. American audiences like a story. They like a narrative to hang their humor on. Performing in Australia or a place like Edinburgh, they'll accept any crazy old thing. It can come completely out of left field. Americans like knowing where the joke's placed. That's a great thing to learn, something that's strengthened the narrative side of the things we do."
Those things might include mimicking robots, speeding cars, kung-fu fighters or a light-saber battle from a Star Wars film. Or running through a skit, then doing the same routine in fast or slow motion. Or pretending to film a terribly snooty documentary about European mimes. And, despite the tight-knit nature of their act, reading and reacting to an audience.
Playing a town several nights running only adds to that give-and-take.
"I like it," Dundas says. "You get to settle in with a particular crowd. Audiences are all subtly different. It's not something you can intellectualize. It's a feel thing. You feel how the audience reacts. Being in St. Louis for about a week, you get to know the people."
Dundas says there may be a Thwak: The Home Video someday, but for now the Brothers haven't discovered how to translate their live show to film or video. With only a few high-profile live appearances on American TV, their unique brand of comedy is still a word-of-mouth phenomenon. So there's no braggadocio involved when Dundas says, "You do get a lot of people bringing their friends back," later in the run. "They tell them, 'You've never seen anything like this -- and I promise you: You'll have a good time.'"