Yes, “Bachelor Pad” is a spinoff — but with a high-school-reunion-type twist.

“The Bachelor” creator Mike Fleiss says he got the idea for “Pad” after hearing about the “weird little sexual subculture” that’s sprung up among past contestants — on “The Bachelor” and “Bachelorette” –who’ve kept in touch once the cameras went away.

“Because they’ve had these shared experiences on those shows, they’ve come together in a real

way and they hang out together,” Fleiss says.

“They’re impregnating each other, going on these reunion trips to Vegas and Lake Tahoe and going on cruises together — it’s sort of a wild scene, it’s nuts, and some of the tabloids started picking up on that.

“I was hearing about this all the time,” he says. “And I thought, if it’s interesting enough for us to be talking about and interesting enough for the tabloids to be following . . . and the fans are curious about it, we should

create a show to incorporate some of that energy.”

Thus, “Bachelor Pad,” which premieres next Monday night. On the show, 19 “all-stars” from “The Bachelor” and “Bachelorette” are thrown into a mansion in Malibu, where they compete in challenges a la “Big Brother.”

“We wanted fan favorites, memorable characters, and we wanted ’em all to be single,” Fleiss says.

Here, though, each week’s winner gets the chance to date another houseguest of his/her

choice — and, yes, the show incorporates “Bachelor” standbys, including the ubiquitous hot tub scenes and the rose ceremony.

“It’s got roses, hot tubs, making out, picking up — it’s really like the first-ever televised network orgy,” Fleiss says.

“I don’t think I’ve ever seen this much sexuality. All the people are beautiful and single, and they’re just having a great time in the summer heat in Malibu.”

And, Fleiss says, there have been some bona fide hookups.

“Some of them are engaged to be married, and I’m not kidding about impregnation — one of the former ‘Bachelors’ knocked up a former ‘Bachelorette’ from a different season,” he says.

“There’s a really powerful bond that forms between cast members — there are a lot of weird relationships and one-night stands. Some will fizzle out and end in hard feelings, and some will go past the one-night-stand phase.

“They all know each other here — and there’s a lot of baggage and pent-up lust and jealousy and animosity.”