KENNEDY BROS TAG-TEAMED MARILYN!

JFK & RFK's sleazy sex rivalry revealed

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WOMANIZING politicos John and Robert Kennedy not only carried on their own steamy affairs with screen sexpot Marilyn Monroe, they both bedded her on the same iconic night she sang a sultry Happy Birthday to the then-president! In her new coffee table book, 90-year-old showbiz legend Shirley MacLaine claims that Jack and Bobby did a tag-team number on the Some Like It Hot star at an after-party following President Kennedy's 45th birthday celebration at New York's Madison Square Garden in May 1962.

MacLaine, who performed at the MSG festivities, recounts what she saw at Democratic fundraiser Arthur Krim's home later that night.

"Jack Kennedy had just walked out of the bedroom behind me, and Bobby Kennedy had just walked in," she writes in The Wall of Life.

"Marilyn was in the bedroom."