A former nude dancer who became a medical assistant and then a nudie model, 50-year-old hot wife Billie Jean Austin makes her 50PlusMILFs.com debut after causing quite a stir in members' pants at 40SomethingMag.com. This platinum blonde shows off those big tits and shapely legs of hers, talks dirty, licks her nipples and makes herself cum. Billie Jean likes to talk dirty when she's having sex. "The dirtier, the better," she said. She told us she keeps getting hornier as she gets older. And get this: "All my girlfriends have big, fake boobs." Nice. "I often touch my boobs in public. Yes, I catch guys looking sometimes." 50Plus MILFs: Have your boobs ever fallen out of your top? Billie Jean: Mother Nature decided one day to show…