What goes on behind closed doors is again front and center on New York City buses.

Advertisements for the Museum of Sex on buses, which drew complaints last year, are causing a new stir.

To Joann Marrone, a mother of two in Middle Village, Queens, the ads, plastered on bus after bus rolling down Metropolitan Avenue, are inappropriate for a neighborhood with many families.

"I was just shocked. I couldn't believe that the MTA actually agreed to this to make money. Honestly," she said. "I'm a mom and I have kids to worry about."

She wrote on Facebook, "Tired of my 9 year old and her friends pointing it out and asking me what kind of 'museum' is this exactly."

"Most moms agreed with me, that the MTA can find better things to advertise on their buses, and the museum could actually find better places to put it," Marrone said.

This mother agrees: "It is a family-orientated neighborhood. And some things are a little too expressive," she said. "I agree with those that say they shouldn't be on the bus."

Last year, some women bus drivers for the MTA complained that passengers were making lewd comments to them because of ads promoting the Museum of Sex. The MTA said it was sympathetic to the drivers and would move the museum's ads to the back of buses.

But the museum's latest round of ads is sitting in the front again, though MTA officials say there is a key difference: the new ads contain an address for the museum, so riders know it's a real place to visit.

MTA officials said they haven't received any complaints about the new ads.

One city councilman from south Brooklyn, Chaim Deutsch, wants them gone, tweeting on Thursday, "MTA — these ads must be removed immediately. Any ad that provokes harassment should be denied."

A spokesperson from the Museum of Sex did not return a request for comment.

We found many New Yorkers happy to ride along with the Museum of Sex's ads.

"The MTA has a source of revenue," a dad said. "I mean, it's just a museum. You have a choice to either go, or not to go."

"I don't think the word 'sex' is a danger for my kids," one mother said. "I'm rather afraid of people who are around me, not about the word 'sex.'"

The MTA has the right to censor ads that are indecent, but officials we spoke to said it would be difficult to consider these ads that way.