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Oh, that BILLY CLINTON . . . still humpin' around behind HILLARY'S back.  According to a new book, Bill has a "busty blonde mistress" who regularly visits the Clinton family home in Chappaqua, New York when Hillary's out of town.

 

His Secret Service detail refers to her as "The Energizer", and they have standing orders when she shows up . . . quote, "You don't stop her, you don't approach her, you just let her go in."

 

It's not clear if Hillary knows about The Energizer, but HER security people keep in touch with Bill's, so there are no "uncomfortable run-ins".