Gad and Rannells have almost too much fun

Andrew Rannells and Josh Gad, that match made in “Mormon,” are back together and hamming it up again on Broadway.

It’s swell to see them twelve years later, like old friends from college who refuse to grow up. Even out of their pressed white shirts and black ties, they’re still insane cartoon characters come to life.

The “Book of Mormon” duo now star in “Gutenberg! The Musical!,” a hyperactive two-hander that opened Thursday night at the James Earl Jones Theatre, and their old-school chops and boisterous chemistry are why the cute off-Broadway gem has improbably wound up, as Gad’s Bud accurately puts it, “on the weird side of 7th Avenue.”

“Gutenberg!” is on the weird side, all right.

The appealingly nerdy show by Scott Brown and Anthony King has two equally wild identities. Call it “Mr. Hyde and Mr. Hyde.” 

First, it’s a backer’s audition, a barebones sampling of a work for potential producers and investors, of a big-cast new musical called “Gutenberg!” about the German inventor of the printing press, Johannes Gutenberg.

Tough sell, right? When this little show premiered off-Broadway in 2005, that pitch alone was hilarious. A musical about the Bible guy? Couldn’t happen. 

But times they are a-changin’. Now that there’s a Tony Award-winning hit about the life of Treasury Secretary Alexander Hamilton two blocks away, you think, “Sure. Why not?” 

Then, “Gutenberg!” is a show within a show and a mostly complete musical. 

Two New Jersey outcasts, composer Bud and book writer Doug (Rannells), perform every song and scene of their bizarre creation for us in hopes that some chump in the crowd will pay to put it on. 

Rannells and Gad go full out. With the exact same stage personalities we know them for, they bolt around playing every role in incongruous accents — from Cockney to California. And to further differentiate each character, they wear caps that say the name, like “DRUNK” or “ANOTHER WOMAN.” 

How are these amateurs able to afford to put on a showcase at the Jones? Because they’ve received an inheritance from an uncle who died in a hang gliding accident. So we witness a disaster via a tragedy.

Trouble for the boys is that what they’ve written is pretty rotten. The entire plot is brazenly fictionalized (did you know Gutenberg started out as a winemaker with a grape press?) and next to nothing about the title character’s life is true except that he, well, invented the printing press. 

There’s more. Gutenberg’s love interest here is named Helvetica, like the font, and the villain is an evil monk with a vaguely Southern accent who wants to forbid the world from learning how to read. The multiple-personalities score stylistically bounces from “Beauty and the Beast” to “Les Miserables” to pop and gospel.

What makes us smirk is that in the back of our minds, as we watch these two clowns manically perform garbage that they are so deeply passionate about, we all think back to a Broadway show (or three) that was as bonkers or worse.

“Gutenberg!” encapsulates what’s so campy about Broadway. Thanks to deep pocketed fools, ridiculous stuff really does make it, albeit briefly, into glittering Times Square theaters all the time.

The real show “Gutenberg! The Musical!” is far from heinous. But it’s not a 100% laugh riot either. It’s an awfully rich dish. Once you get the gist, you’ve had about enough. 

When it debuted 18 years ago, self-aware musicals — “title of show,” “Urinetown,” “Monty Python’s Spamalot” — were all the rage and in-jokes about “I want” songs and Act 1 finales had a system-breaking edge. That shtik is old hat these days, even when the gags are so intricately choreographed by director Alex Timbers, whose knack for humor shines in smaller fare like this, “Bloody Bloody Andrew Jackson” and “Oh, Hello!”

Our interest in the fake “Gutenberg!” especially wanes in the second act. I tended to prefer the direct-address portions, in which Bud and Doug discuss their artistic process or tell us secrets about their lives, over the repetitive songs and dances.

But Gad and Rannells — what a pair — are always a pleasure to watch. And when they really nail a joke, it lands like a jumbo jet.

“Every musical needs to tackle a serious issue,” Gad’s Bud says early on. “Like racism, homophobia… or a man with half a face.”