You get G.I. Joes for Christmas. Hooray! You make them cross the demilitarized zone between the china cabinet and the pile of DVDs near the TV to rescue Barbie. Pow pow pow — enemy fire. You throw rocket grenades at the bad guys. You win!

New toys! Exploding cluster-bomb motorcycle! Ninja Joes! You infiltrate Pakistan, right over that ridge in the backyard, and steal back the nuclear weapons (played by spools of thread stolen from Mommy’s sewing kit) from the bad guys (played by your sister’s Lord of the Rings elf dolls). Ratatatatatat — machine gun fire. You make the Joes punch the elves. You win!

It’s your birthday. New toys! You get the G.I. Joe airboats. You make the Joes chase the masked guy across the puddle in that pothole in the street. Oh no! You knock over the juice boxes on the curb. Cobra Commander just destroyed London! You win this time, Cobra Commander!

Forgive me. I’m making G.I. Joe: Retaliation sound like a helluva lot more fun than it is.

It’s nowhere near this coherent, either. Probably the most coherent moment, in fact, is when Jonathan Pryce, as the president of the United States, is required to say, “Get me the G.I. Joes.”

We talk about “live-action cartoons,” but perhaps no movie has ever come nearer to such a thing than Retaliation. Because no one else laughs, either, when Pryce says that. Although, to be fair, this is a world in which the official Pentagon assessment of a Pakistan in turmoil after its president is assassinated is: “It’s a riot with a zip code.” (Pakistan probably has lots of zip codes, silly!) And this is also a world in which, apparently, everyone lives in fear of a supervillain who calls himself, in all seriousness, “Cobra Commander,” and yet also a world in which the president of the United States can later announce that his new elite fighting force (replacing the Joes, who are on the outs for reasons less plausible than the plot of a backyard military toy campaign) is called Cobra. Oh, and his Secret Service detail are all wearing Cobra lapel pins that are plainly apparent on national television. How did no one catch on that the “President” is actually another dude entirely who’s secretly wearing a nanostuff Jonathan Pryce disguise and is working with Cobra Commander to try to take over the world? I mean, sheesh, people.

Again, I’m making this sound far more entertaining and logically consistent than it is.

Retaliation purports to have been “written,” but that seems unlikely, particularly when credited screenwriters Rhett Reese and Paul Wernick are previously responsible for the witty Zombieland, which also featured “characters” and “themes” and a “story.” The only relatively lucid thing Retaliation has on its side is an “in association with Hasbro” credit, which makes you go, “Ah, they tried to make something with all the pizzazz and credibility of a toy commercial. Pity they failed.” It’s almost as if no one — up to and including the cast — actually read the “script” before they started shooting, or even while they were shooting. In one bit, nominal hero the Rock intones ominously that there’s only one person whom he and the other two remaining Joes (D.J. Cotrona and Adrianne Palicki) can trust, now that the Joes as a fighting force have been betrayed and killed, which could only have been ordered at the highest level. Half an hour later in the film, the Rock is mumbling portentously about the “one person I trust,” and it’s someone else entirely. (One of them turns out to be Bruce Willis, who looks pained to be here, as well he should. He’s the original GI Joe.)

It occurs to me that all this “someone else entirely” stuff infecting the film may be evidence of attempts at mass exodus on the part of the previous film’s cast, who when they finally did read the script saw fit to make a quick escape. It could explain why Channing Tatum makes an early exit from the film, in which case we must be thankful for small favors. Retaliation may be powerfully stupid, but it could have been worse: Tatum could have been in all of it.