Is it a rare chance to see a famous Gen X actor, Jack Black, perform live? Or do that many people really love Black’s musical comedy act Tenacious D?

Whatever the case, Tenacious D has sold out two nights at the Palace Theatre in St. Paul this week. On Tuesday, nearly 2,800 fans laughed and howled, sang along and rocked, and chanted “D, D, D” like this was the second coming of Led Zeppelin.

Is Tenacious D a rock band as theater or theater as a rock band?

After Tuesday’s 110-minute show, the answer would be “Yes” to both.

Black is so skillful at playing the rock star — or himself, some would say after his triumphant role in the movie “School of Rock” — that he can not only act like one but sing like one.

Granted his voice is more Broadway than Madison Square Garden, but he can deliver a heavy-metal scream, hard-rock growl and pop croon as well as rap and scat. And he threw in some Broadway-ish balladeering, too. Who cares that none of it seems sincere? That’s part of the appeal of Tenacious D.

While the Blues Brothers were a silly homage to the blues and Spinal Tap a serious satire of British metal, Tenacious D is a hilarious sendup of hard rock.

The D — that’s Black and wingman/lead guitarist Kyle Gass — started out in 1997 as an HBO series before becoming a recording act. The duo garnered enough respect to get members of Foo Fighters, Queen and Guns ‘N Roses to record with them. Over the years, Tenacious D has opened for such heavyweights as Pearl Jam and Tool.

While Tenacious D was once nominated for best comedy album, the group gained some musical cred in 2015 by winning a Grammy for best metal performance over Mastodon and Motorhead.

Tuesday’s show opened with comedic side of the D. With the help of animated drawings, the duo recreated its fourth and current album, “Post-Apocalypto,” in its entirety.

For 40 minutes, Black and Gass stood behind a scrim and played the occasional song as drawings and dialogue told the tale of how the duo survives the apocalypse, gets propelled into outer space, steals a magic Egyptian crystal from the White House and saves the world — while having lots and lots of sex along the way.

In short, it was typically weird D with its juvenile humor and heroic vocal glory (loved that grizzly Axl Rose-like yelp near the end).

Then, it was time for greatest hits.

Part of what makes the hits — or bits — work is that Black, 49, and Gass, 59, burly bearded dudes in T-shirts, are backed by three well-schooled musicians. But the frontman have so much fun with each other.

There was the mock argument with Gass stalking off the stage before Black started “Dude (I Totally Miss You).” Of course, Gass returned mid-song for his guitar solo.

Black implored the crowd to dance during the funk instrumental “Sax-a-Boom,” a sonic outlier in the set, before the D rocked their faces off on “Kickapoo” and the riotous “Beezleboss.”

“Only five people can defeat the devil,” Black explained afterward. “Robert Johnson. Ralph Macchio in the movie ‘Crossroads.’ Jimmy Page. Charlie Daniels in ‘The Devil Went Down to Georgia’ and Tenacious D.”

Call it another victory for the D.