Legendary comedy scribe Bruce Vilanch is renowned as the go-to for award shows but he’s also been involved with some deliciously campy specials and movies.

The Emmy winner recounts them in his predictably hilarious upcoming memoir, “It Seemed Like a Bad Idea at the Time.”

One NSFW moment occurred on the set of “The Brady Bunch Hour,” a short-lived shlock-fest that ran for a few episodes in 1976-77.

Vilanch remembers that the squeaky clean Donny and Marie Osmond were guest-starring and due to their massive popularity, the sibs had doubles to fool over-enthusiastic fans.

One day, Marie’s agent, an up-and-comer named Mike Ovitz visited with three other reps.

Marie’s double, who was a dead-ringer for the perky singer, went up to Ovitz to chat after conferring with a wicked comedy writer.

After introductions, she sweetly told Ovitz, as a prank, according to the book: “I would like you to come to my dressing room,” to, shall we say, engage in a sex act that can’t be described in a family newspaper.

There was “stunned silence… everyone just froze… then the dime dropped and everyone got it at once.” Vilanch calls it the “single most hilarious and obscene example of what can happen when preparation meets opportunity.”

The “Hollywood Squares” alum also remembers “Brady Bunch” mom Florence Henderson as “a much more colorful mother than Carol Brady” who would occasionally unleash “a small repertoire of dirty jokes which she liked to surprise the unsuspecting.”

The Post’s Nicki Gostin reports that Vilanch writes in the book that he worked on the infamous 1989 Oscar ceremony featuring that awful Rob Lowe opening number.

Vilanch swears he had nothing to do with it, and voiced his concerns to the show’s producer, who flitted away any dissent.

The jokester also gleefully dissects his time working on the Village People movie “You Can’t Stop the Music,” and more.