Billed among dance and theater programming in venues across the nation and around the world, the Umbilical Brothers’ performances can scarcely be described in terms of dance or drama alone. Add physical comedy, invoke vaudeville and garnish with a generous helping of silliness to begin to approximate what’s in store.

Former acting school classmates, Shane Dundas and David Collins have said they learned together the “foundations of modern performance: lack of confidence [and] abject poverty.” Upon “deciding that mime classes aren’t loud enough,” they assembled an act of their own, unequivocally louder and certainly more outrageous, one that would become the first of many. Initial runs of their material produced the desired effect — laughter — and the Umbilical Brothers were born in 1990.

In the first year of their endeavor, they won first prize at a stand-up comedy competition in Sydney and took grand prize in Australia’s “Star Search.” The dynamic Aussie duo had audiences rolling in their seats throughout Australia and began touring extensively, spreading hilarity in the United States, Europe, South Africa and more. In the past two decades, they have performed in fringe, comedy and mime festivals, at traditional theaters and Woodstock, the Tonight Show with Jay Leno, Late Night with David Letterman and more.

“THWAK,” created in 1999, was the first of their productions designed specifically for American audiences sans cultural translation. That same year, they were listed in Entertainment Weekly’s “100 Most Creative People in Entertainment,” one of many awards and distinctions they’ve garnered over the years.

Called “an uproarious fiesta of carefully choreographed mayhem,” Dundas and Collins weave their acute sense of comedic timing, artistry with silence and sound effects, and enviable physical control with a propensity to clown around. The Umbilical Brothers’ strain of physical theater toes a fine line between the intelligent and the immature, resulting in a comical but clever program with some explicit language and references that might make parents wary of bringing young children along.

In quite the poignant passage of friendly competition, the two brainstorm and demonstrate endless ways to flip each other off — from slingshot and windshield wipers to “read between the lines.” Their little tiff dissolves as they ask the audience to suggest various sports they could enact to creatively give each other the finger, ending with a ploy to give them the finger, which had ostensibly flown beyond the footlights in a sword fighting accident.

As they slip back and forth between choreographed material and improvisation, Dundas and Collins’ comedic chemistry never abates. Though they are not in fact biological brothers, the ease of their onstage antics would suggest otherwise.

Dundas and Collins will perform “THWAK” in Pigott Theatre as part of the Lively Arts season on Saturday, Feb. 12 at 5 p.m. and 9 p.m., and Sunday, Feb. 13 at 7 p.m.