Madonna surprises college students.

The former Material Girl surprised students at a film course who had just seen an advance screening of her tour documentary, "I'm Going to Tell You a Secret."

Her appearance was filmed for the mtvU network series "Stand In," where celebrities such as Marilyn Manson, Bill Gates, Shimon Peres, Melissa Etheridge and Kanye West have appeared as guest lecturers at colleges. . . . . .Full Story