The Street Theater Company’s “Social Insecurity (an Operetta for the Streets)” is an overly sincere, artistically invalid bit of street agitprop. That said, it’s relatively harmless, and thankfully, it’s a musical, not actually an opera.

The story follows three teenage friends (played by 30- and 40-somethings, of course) who are full of naive optimism about the future. Clearly, the “harsh reality” of merging corporations, outsourcing to India, and “war for oil” is about to come crashing down on them. And it does, when they are all sent to Iraq.

The characters share an absurd obliviousness to the implications of joining the military. One goes because he’s from a military family; another goes for college money. In a telling example of the play’s devotion to truth, the third is arrested after the police bungle a drug bust.

A strung-out addict throws a giant sack of cocaine at the innocent hero’s feet, prompting one officer to ask, “Which one should we take in?” “Take the one closest to the drugs,” the other shouts. He gets “alternative sentencing” and is sent to Iraq. This isn’t satire, and it isn’t funny.

Humor is the left’s best weapon, and activists who choose not to use it do so at their own peril. At worst they end up in so bad it’s funny territory, as here, when the ghost of a blown-up soldier informs his friends, “You may take my body. But my soul will never rest. Because of the injustices. I have. Seen.”

In the most hilarious subplot, the ghost returns to America with his two buddies, appearing on stage occasionally to stare at the audience serenely with sad, enlightened eyes. When he discovers that Americans are protesting, the eternal burden is lifted: “People are beginning to wake up. Maybe I can rest now.”

The ghost is supposed to be symbolic of something, I guess, because two separate characters comment, “I think he’s going to be with us for a long, long time.”

And then there’s the portrayal of President Bush, whose cameo is all but inevitable in a play of this ilk. He is – surprise, surprise – Dick Cheney’s puppet. While attached to strings, he trumpets nuclear power as an alternative energy source, raving, “We could blow up the entire world!” They aren’t even spoofing Bush. They’re spoofing the spoof of him they’ve seen in all the other shows like this.

The play would be completely incoherent if it weren’t so derivative. We know what’s happening because we’ve seen it in various incarnations hundreds of times. If it weren’t for the songs, which have lyrics that mostly rhyme, I would have suspected that writer/director Crystal Field penned “Social Insecurity” overnight in a fury of political indignation, perhaps after an especially agitating “Daily Show” binge.

Though there have been a thousand political shows like this one, all probably more timely, “Social Insecurity” will mildly amuse its intended audience of moderate anti-war liberals who are “for the troops, but against the war.” It’s not incendiary enough to get riled up about. And it’s not quite bad enough to enjoy ironically. But – as it is free – if you happen to find yourself at the corner of Marcy and Tompkins, waiting for a bus, should you turn your head and watch for a few minutes? Sure, why not?

“Social Insecurity” will be performed in parks and streets in all five boroughs until September 18. See www.theaterforthenewcity.net for more details.