There’s no denying Tenacious D is funny: Jack Black and Kyle Gass have perfect pitch when it comes to their parodies of heavy metal and classic rock cliches, seen over the last five years in a trio of half-hour HBO shows and a series of local appearances. The shows, more skits than full-blown concerts, were a post-collegiate variation of “Wayne’s World,” showcasing Tenacious D for an audience that got the in-joke and looked back on the excesses of ’70s and ’80s rock with the same mixture of affection and horror. With an album due this year from Epic Records, the question dogging the “D” is: Will they be able to expand both their act and their audience?
The prognosis, based on their appearance at the Palace, is mixed. The self-proclaimed “greatest band in the world” still generates grins simply by showing up; the shtick of two ordinary-looking guys taking the stage with the gaseous self-regard of heavy metal gods is incongruously amusing. And Black, an actor who delivered a star-making performance in last year’s “High Fidelity,” is a gifted mimic. His imitation of Axl Rose early in the show hit the target dead-on, and he can flex his voice from a screechy Robert Plant to the portentous basso profundo of Ronnie James Dio.
But the subtleties (such as they are) of their humor were lost on the sold-out audience at the Palace. The crowd responded to parodies of heavy-metal lyrics and their faux-medieval images of sprites and wizards with seemingly un-ironic nodding heads or by singing the lyrics back.
The biggest laughs came when the band resorted to the toilet humor of their newer material, with “ka-ka pee-pee do-do” jokes elbowing out musical gags. If this keeps up, it’s possible Tenacious D will become another played-out joke, a punchline for the next generation of pop culture pranksters.