It was the meeting of pop royalty when Lady Gaga took in Britney Spears' Femme Fatale show in New Jersey's Hotlantic City this weekend.  The crowd went bananas when Spears opened the show announcing, "I have a very special guest tonight...Lady Gaga is here!"  Gaga stood, waved, and threw out a heart symbol. Britney promptly hearted her back, birthing the next "high five" amongst tween girls and gays across the country.  Mother Monster was later spotted double fisting drinks and hitting up the blackjack tables at the Borgata Resort, letting fans know that she too has the vice-succumbing potential of her popstar counterpart.