Sex: The Annabel Chong Story (1999)

Sex: The Annabel Chong Story is a 1999 documentary film directed, filmed, and produced by Vancouver, B.C., Canada based producer's Gough Lewis,Kelly Morris and Peter Carr and edited by co-creator [http://www.imdb.com/name/nm1074050 Kelly Morris]. The film profiles porn star Annabel Chong (born Grace Quek), a gender studies student at the University of Southern California, who was also an adult actress famous for setting a world record by having sex 251 times with 69 men in ten hours in January 1995. A video of this event was released under the title The World's Biggest Gang Bang.

More at Wikipedia.