What a relief. “Ghost Rider” is a joke — a monumentally foolish comic book movie with lots of unintentional laughs, mixed in with the intentional ones.

Absurd, ineptly plotted, it lacks a coherent theme or storyline or reason to exist aside from a very silly Harley-from-Hades burning motorcycle effect.

They cast Nicolas Cage to star in it, but you cannot tell if the burning skeleton version of him on the bike is him at all. Not his physique, not his voice.

Director Mark Steven Johnson (“Daredevil”) blows it, not quite completely.

But a relief, why? Because if movie studios start hiding good $120 million comic book movies from reviewing critics before opening day, well, the game is up for we poor, downtrodden reviewers.

Nic, dolled up in Elvis leather, drawling the role of Satan’s Skip-Tracer, the Devil’s Bounty Hunter on a Hog, makes the jokes work. The intentional ones, anyway. As Johnny Blaze, a stunt-biker who sold his soul to the Devil (Peter Fonda, stiff as a corpse) he’s into death-wish stunts, jellybeans in martini glasses and maudlin Karen Carpenter ballads. Whatever you do, don’t touch that stereo.

“Dude, you’re steppin’ on Karen!”

Eva Mendes is the girl he left behind after he sold his soul to save his dying dad. She’s a TV reporter now, toting around a microphone that looked fake even when “American Bandstand” was lip-syncing its way into history. You aren’t meant to notice the mike, or that she leaves the scene of her “big story” without actually taping the stunt the story is about (DUH). You won’t notice because girlfriend is seriously popping out of every blouse they give her. A $120 million budget and they couldn’t find her a shirt that fits? I kid.

The Devil has this contract he once failed to collect. An earlier Ghost Rider kept it from him rather than relegate humanity to some awful fate (a hell where all the multiplexes are showing “Ghost Rider”?).

Try not to laugh

And now the Devil’s son, Blackheart (the juvenile Wes Bentley) wants it, to depose Daddy. The “new” Ghost Rider stumbles into The Caretaker, perfectly growled by Sam Elliott, who gives him advice on riding without a helmet, and other really important questions.

“Is this thing ever gonna end?”

“Not even close.”

Unintentional laugh. Big one.

There’s nothing compelling about that plot. The “menace” that this spawn of Satan poses to humanity, or to Eva Mendes, is yawn-worthy. The “cool” cycle isn’t that hot. The pandering ’70s-rock soundtrack is eligible for Social Security.

But Cage almost, almost makes it campy enough to work. He hits his marks, looks so ripped and mop-topped that you’d swear his six-pack and hairline are special effects, and he never breaks up, even when he’s drawling the stupidest lines.

“I shore wish this thang coulda turned out different.”