For decades now, irony has seeped into every pore of the entertainment industry. It just took a little longer to saturate that stronghold of the over-earnest, musical theater. You could argue that Sondheim has been chipping away at Broadway’s grin since the ’70s. But his work doesn’t give the blatant wink of the meta-musicals that have colored our current decade.

“Gutenberg! The Musical,” the off-Broadway cult phenom now in the New Repertory Theatre’s black box space, certainly isn’t the first of its breed. But it definitely ranks among the funniest.