As big, dumb summer “entertainments” go, they don’t get much bigger or much dumber than “Transformers: Revenge of the Fallen.”

The briefly amusing mash-up/crunch-up of a couple of summers back has been recycled into an epic two and a half hours of explosions, ponderous cartoon history, veiled racism and inept geography.

Is it the worst movie of the summer? Possibly. Will everybody see it? Probably.

“Revenge of the Fallen” means that the robots that supposedly were terminated in “Transformers” have back their “spark,” led by “The Fallen.” They have big plans for this planet that they first discovered thousands of years ago. It’s up to Optimus Prime, the Autobots and their human allies to stop them.

Only the government doesn’t trust our beloved Camaros that convert into killer robots. They’re convinced the ’bots are the magnet that draws the evil Decepticons to Earth for their little brawls. The military men just shake their heads at this civilian foolishness.

“We’ve shed blood, sweat and precious metals together!”

Meanwhile, the idiotically named Sam Witwicky (Shia LaBeouf, not touching that one) is off to college, where he’s pursued by alien co-eds and rescued by the comically attractive Mikaela (Megan Fox). Sam is connected to these transforming beasties by his past and an imprint on his brain.

As with the last “Transformers” movie, the early scenes work best. LaBeouf does a great motor-mouthed patter as Sam hallucinates visions of alien hieroglyphics and maps, annoying his astronomy professor (Rainn Wilson, funny in his one scene) and frightening his player/entrepreneur roomie (Ramon Rodriguez).

At some point, the funny patter and goofy-mom (Julie White, fearlessly foolish) moments end and it’s all about the metal on metal as we circle the globe, sink an aircraft carrier and trash a pyramid or two in an effort to fend off human extinction.

Director Michael Bay decided he liked the laughs of the first 40 minutes of the first “Transformers” movie, so he pushed more laughs into this one – parents-eating-hash-brownie jokes, robots-humping-Fox’s leg jokes, robots trash talking, cursing and acting very street.

Two of them have gold teeth, profess to be illiterate and speak a version of “jive” that must date back to “Starsky & Hutch.”

Bay came all the way to America from Britain, built a career on “Bad Boys” movies, just to put robots in blackface?

But here’s where “2.0” is better than the original. The GM cars are cooler. The effects are sharper, higher-definition. None of that blur of chrome and steel that made the first film’s fights so tedious.

TRANSFORMERS: REVENGE OF THE FALLEN

*

Director: Michael Bay

Cast: Shia LaBeouf, Megan Fox, John Turturro, Rainn Wilson

time: 2:31

Rating: PG-13; intense sequences of sci-fi action, violence, language, some crude and sexual material, and brief drug material

Where: In wide release; showtimes on Page C2.