Hugh Hefner is putting his official stamp on the latest issue of Playboy magazine featuring his ex bride-to-be Crystal Harris ... but the stamp is in the form of a red sticker!

After news broke that Crystal decided to not marry Hef this weekend at the Playboy mansion, the 85-year-old Playboy founder added a red sticker to the July issue that reads "Runaway Bride In This Issue." Ouch! That's one way to address the headline, "Introducing Mrs. Crystal Hefner."

Despite thousands of copies already being shipped to newsstands, Hefner has ordered that all copies get this red sticker.

Crystal hit the airwaves yesterday with Ryan Seacrest on KIIS-FM to discuss why she had a change of heart. Surprisingly, she sounded quite chipper. Looks like Hef is having the last laugh. Revenge is sweet!