How do they do it?

I was in the studio waiting for my hit in the show, and a package was running about a teacher named Mateo Tirrilium. During the package, the anchors are usually talking with each other and many times they'll make jokes.

One of them said "Tirrilium…isn't that number 43 on the Periodic Table?"

The other, "Actually, I think that's the amount of our federal deficit. One Tirillium dollars."

This all happens in the last 10 seconds or so and soon they're back on camera and having to say "Mr. Tirrilium" wither seriousness. I couldn't keep from snickering, so I don't know how they do it...