By Denise Martin, Kate Stanhope, Jevon Phillips and Patrick Kevin Day, Times Staff Writers Eminem and Sacha Baron Cohen rigged their entire close encounter on the MTV Movie Awards? No way. Spencer and Heidi walk off NBC's "I'm a Celebrity...Get Me Out of Here," and then NBC sends out a press release that the couple was "begging" to be let back on? Hmmm. Is nothing real in this crazy TV world anymore? Maybe, but it's getting more and more difficult to dupe the jaded masses. We look back on small-screen stunts, past and present, that have tried, sometimes in vain, to fool for fun.