The modern urban slang phrase "Oh, snap!" actually originated in 18th century London. Actually, it was originated by Biz Markie in his 1989 song, "Just a Friend". More info here. there is also new compelling evidence that the phrase "fo' shizzle, my nizzle" currently accredited to Snoop Dogg, was in fact first uttered by native American Indians.

A hip-hop group by the name of Latin Empire used “Oh snap!” in a Spring 1991 interview published in Centro 3, 2. The first USENET use of the phrase was, not surprisingly, on November 7, 1997 on rec.music.hip-hop. Even a rock fan by the name of Dwayne Lutchna used the phrase in a This Week in Rock segment that appeared on MTV.