Umbilical Brothers Have ‘Thwak’-y Sense of Humor

“Thwak” is an Australian word signifying a footstep (thwak), or footsteps in succession (thwakthwak-thwakthwak). It’s also the sound of an arrow hitting a tree--THWAKdoiiiiiing. The word is an active verb, as when exploding dog-guts thwak someone in the face.

Lots of imaginary animals come and go, quickly and often violently, in this raucous show written and performed by a couple of guys from Sydney.

A feast of “silly noises” (the show’s description, not mine) wedded to improbable sights, it’s the work of the Umbilical Brothers, also known as David Collins and Shane Dundas. The Umbilicals have been on Leno and Letterman. They created the voices and sound effects for Nickelodeon’s animated series “Maisy.” “Thwak” has toured all around the world. It is very much a Fringe Festival-type show, heavy on the Stooges-style slapstick, somewhat abstracted.

At its best, “Thwak” is a blissfully stupid lark, featuring a deft, live, low-tech soundtrack.

In this universe, he who controls the microphone controls the silly noises. And he who controls the silly noises controls the other guy’s fate. Curly-mopped Collins, assigned to the role of “action guy,” looks a bit like long-faced John Lynch of the movie “Cal.” Eagle-eyed Dundas, initially the keeper of the mike and controller of this universe, also sports a longish, appealing mug.

Dundas and, later, Collins create an infinite storehouse of sound. Galloping horses? Door bolts? The whir of a descending elevator, or the world’s fastest tap-dancer in action? They’re all here. When one man makes with the noises, the other provides a direct visual corollary. Or else, he doesn’t--which is pretty funny too.

To be sure, “Thwak” takes aim at its share of hoary comic targets. Among them: mimes, Asian martial arts movie dubbing, self-indulgent lounge entertainers. Still, when Collins or Dundas points an invisible quill at a target, familiar or otherwise, the resultingsound of arrowhead-on-wood is bound to be utterly right.

At one point in this 80-minute affair’s first half, Dundas and Collins become Hans and Klaus, humorless practitioners of “European visual comedy.” (Germany could sue for defamation.) The second half meanders here and there, especially in an extended routine featuring Collins’ promised “five hours of uninterrupted ballads” (thankfully interrupted by Dundas vacuuming the stage).

The climactic dueling-microphones battle makes up for the pokey stretches. Even with the occasional f-word, this is a show for the 13-year-old boy in most of us. Also, in this City of Show Biz Industry, it serves as a handy live-action audition reel for its makers. Surely the Umbilicals should get a voice-over gig or two out of the L.A. run of “Thwak.”

BE THERE

“Thwak,” Tiffany Theater, 8532 Sunset Blvd., Hollywood (parking entrance off Alta Loma). Tuesdays-Fridays, 8 p.m.; Saturdays, 7 and 10 p.m.; Sundays, 3 p.m. Ends May 21. $37.50-$45. (310) 289-2999. Running time: 1 hour, 20 minutes.