Avenue Q at The Orpheum

The darling muppets, who loiter on the clean-scrubbed stoops of Sesame Street, are beloved, it’s true. But like all things bright and shiny and incessantly innocent, it’s kinda tempting to sully them a bit.

Which is why shows like Avenue Q have had such success. What was once an Off-Broadway parody of Sesame Street — featuring a porn-loving monster and hot felt-on-felt action — became a Broadway hit, spawning a Vegas show and a national touring company. Smirking at sanctity is no longer a fringe fetish.

The rumor that Bert and Ernie are boyfriend and boyfriend has been bandied about since the first Sesame Street graduates hit puberty. There’s something inherently funny in thinking about wholesome children’s puppets in adult terms.

It’s funny because it’s perverse — the notion, that is, that these strictly waist-up lovable naifs have a life below the waist.

There’s a fine tradition of sullying G-rated iconography with our dirty little minds and revamping childhood staples with the not-so-sunny realities of life outside of PBS children’s programming.

Remember, if you will, the sublime SNL parodies of Mr. Rogers’ Neighborhood, with Eddie Murphy as a ghetto version of the friendly cardigan-wearing neighbor, “Can you say scumbucket?” he ask the camera after receiving an eviction notice from his landlord.

On Avenue Q, folks are more upstanding, but life is still disappointing. “What Do You Do with a B.A. in English?” sings Princeton, a recent college grad, (who happens to be an orange-skinned puppet). Scouting out a cheap apartment on a familiar-looking block of brownstones, Princeton encounters Gary Coleman, (queue the comedy of nostalgia) who, inexplicably, is the building’s super. The former child star turned sad sack is on hand to further illustrate that Avenue Q is the boulevard of broken dreams.

The promises of childhood (every one of us is worthy and special and respected, yada yada) turns out to be as flimsy as that charming brownstone facade.

“It Sucks to Be Me” is Avenue Q’s musical retort to the ethos of Bob and Big Bird’s cloying “Aren’t You Glad You’re You?”

And it’s the clash between TV idealism and “reality-based” reality that makes some of us want to pop their balloon. Most parents want to shoot Barney, don’t they?

There was the similar impetus at work in The Brady Bunch Movie. It’s really satisfying (to those of us who had our face smooshed against the window of that split-level suburban home) when that bunch of Pollyannas gets real life thrown at them.

You actually don’t even have to leave the real PBS Sesame Street to find that reality is getting in the way of old school happiness; These days the cookie monster advocates a balanced diet, loves his veggies and tells kids “A Cookie is a Sometimes Food” (Damn you Michelle Obama!)

While the Tony Award-winning Avenue Q (conceived by Robert Lopez and Jeff Marx, who wrote the music and lyrics, book by Jeff Whitty) strives to be irreverent — some muppets are gay and some are porn addicts or sluts. Songs have titles “You Can Be as Loud as the Hell You Want (When You’re Makin’ Love),” “Everyone’s a Little Bit Racist” and “Schadenfreude.” But in the end, it’s really just another felt boy-meets-girl monster, felt boy-loses-girl monster story.

Avenue Q runs through February 27, 2011 at The Orpheum Theatre in San Francisco. For tickets and information visit shnsf.com or call 888-SHN-1799