The "National Enquirer" claims a LOT of sex happens behind-the-scenes at "Dancing with the Stars" . . . and they're blowing the lid off of it.
--A so-called "production source" says, quote, "The number of affairs has gotten way out of hand. There's been so much casual sex behind the scenes that you'd think it's a swingers club, not a dance show."
--They posted a rundown of some of the alleged hook-ups, including:
--Derek Hough: Shannon Elizabeth and Maria Menounos
--Julianne Hough: Helio Castroneves and Chuck Wicks
--Mark Ballas: Shawn Johnson and Sabrina Bryan
--Maksim Chmerkovskiy: Karina Smirnoff, Willa Ford, Erin Andrews and Peta Murgatroyd
--Cheryl Burke: Chad "Ochocinco" Johnson, Drew Lachey and Rob Kardashian