A walk down memory lane turned into a scream of shock and anticipation for Jennifer Lopez on 'The Tonight Show.' It started off innocently enough, with Jay Leno asking her about her big break into the world of professional dancing.

"I got a job working as a back-up dancer for New Kids on the Block," she said. "Dancing on the American Music Awards and it was a big deal."

That was back in 1991, "a long time ago," according to Lopez. "There's tape out there somewhere, for sure," she said.

That's when Leno announced, "In fact, we have it right here." And she screamed.