DALLAS, Texas, May 7, 2008 (NBC) -- A special group of "doctors" at Children's Medical Center in Dallas, Texas are hoping to help cure patients with comedy, but they didn't go to medical school to learn their trade.

For Tiffany Riley and Sean Petrello, going to work means going to the hospital and spending time in clinics and rooms; being clowns.

The kids at Children's Medical Center in Dallas know them two best as Dr. Slappy and Dr. Yawk.

"We have a party and we dance. We get the parents involved," said Riley. "And we get the kids to forget what they're doing here, even for a few minutes."

For kids, including Derrick Sells, who has sickle cell anemia, the clowns give him something to think about other than his disease.

The laughter of the clowns takes the kids minds off of the pain and keeps the two comedians coming back to a job they love.

"When you see that child smile or laugh or crack up then you know what you're doing is something really cool," Riley said.

It's a job where laughter is a requirement.

The clown program at Children's started out on a volunteer basis, but now the hospital has a staff of nine clowns working part-time.