Oprah Winfrey Says 'Ugly Cry' During Mary Tyler Moore Surprise Led to This Rule on Set (Exclusive)

When Mary Tyler Moore emerged from backstage as a surprise guest on The Oprah Winfrey Show in 1997, Winfrey immediately dissolved into tears. Moore was one of her longtime role models, and the talk show host was left all but speechless on-air. "I went into the ugly cry," she tells PEOPLE in an interview celebrating the magazine's 50th anniversary. Never again. "I said, nobody will ever surprise me again [and] if you want to continue to work here, do not surprise me!" she recalls, with a laugh. The lone exception...