NEW YORK, New York -- 'Saturday Night Live' is known for its surprise celebrity guests, but on Saturday, the NBC late night show had a big night even by its own standards. Lady Gaga, the show's musical guest, was joined in a comedy sketch by one of her idols - Madonna. The two singers - dressed in revealing lingerie-like outfits - fought over who was the bigger star before being separated by Keenan Thompson during an MTV-style 'Deep Dish House' segment.