Happy bail-day, to yooou!

Not only is the Robert F. Kennedy foundation indiscriminately bailing out jailbirds — including many with violent raps — it has now parked a welcome wagon outside Rikers decked out with banners, party balloons and birthday-like sheet cake.

The group plopped an air-conditioned shipping container, complete with port-a-potty and gas-powered generator, between two “No Standing” signs on 19th Avenue near Hazen Street in Queens, right near where the bus from Rikers makes its first stop off the island, to serve as a welcome center for the freshly freed.

But the makeshift House of No D, which is draped in banners that read “Mass Bail Out” and “Welcome Home,” should still be a familiar site for its patrons — all its windows are covered in bars.

On Monday, volunteers from RFK partner NYC Crisis Management System, which is staffing the center, lined the sidewalk with balloons and yellow chrysanthemums, and a “welcome” mat was spotted inside the pod, where they also hand out snacks, MetroCards and cellphones to former inmates.

But the welcome wagon has no permits to be parked in the no-standing zone, according to Transportation Department officials.

A volunteer at the welcome center claimed the group got permits but declined to elaborate.

Seeing photos of the arrangement, a police source groused: “I’m all for bail reform. But they’re just going on a rampage and letting anyone out.

“That’s like, ‘We’re going to bail you out. We’re going to feed you and go out there and commit some more crimes. We got your back,’” the source said.

The RFK Foundation plans to spend $5 million bailing out hundreds of women, as well as 16- and 17-year-old boys and girls, despite their charges or criminal histories — a move that the mayor, police commissioner and all five city district attorneys have said is a bad idea.

Among those sprung so far are an ex-con who did two and a half years in prison for assault convictions, a woman arrested for prostitution seven times, and a teen who allegedly choked a cabbie and robbed him at knife-point.

The charity cut the ribbon on the welcome wagon on Saturday, according to tweets by Borough President Melinda Katz.

“#Queens believes poverty is not a crime and wealth-based pre-trial detention is morally wrong. The #MassBailOut, with a focus on bailing out women and children, is about strengthening communities, and builds upon years of collective work by so many to end mass incarceration,” Katz wrote, along with photos of her smiling as she helped open the center.

“Proud that #Queens, the borough closest to #Rikers, can host it and build community support around it. If it’s good for families, it’s good for #Queens.”

Councilmen Costa Constantinides and Jumaane Williams were also on hand. Neither the foundation nor Katz’s office responded to inquiries by The Post.