They were among the 16 contestants who entered the Big Brother House in June, and spent the summer trying to outplay each other in often-wacky weekly challenges. On Sunday night, Clark and Mounduix will compete against Tyler Crispen, a lifeguard from Hilton Head, S.C., for the final two spots and, ultimately, the $500,000 grand prize. “Big Brother,” the raucous CBS reality show competition that will end its 20th season on Wednesday, hit a milestone on Thursday night, with a Final Three that included two LGBT contestants: Kaycee Clark, a professional football player and out lesbian from Tempe, Arizona and Joseph “JC” Mounduix, an openly gay dancer from West Hollywood, Ca. Watch Video: RuPaul honored with star on Hollywood Walk of Fame