PALO ALTO, Calif. -- Late one spring afternoon last year, a mystery man sat in the back of a creative-writing seminar at Stanford. Evidently a student, he was much older than anyone else in the room. He was wearing a black blazer and white Nikes. He said his name was Phil.

As the days passed, the man's identity gradually came into focus. The instructor "made several vague allusions to Phil taking off in his private jet," recalls André Lyon, an English major enrolled in the class. And tales about Michael Jordan found...