On 12/17/2008, Craig Ferguson (Late, Late Show on CBS) read a viewer email from "Jason" in Louisville, KY, which prompted him to teach the audience how to pronounce "Louisville" so they won't know you're from out of town.
The bit can be found about 4 minutes, 15 seconds into the clip at:
http://www.youtube.com/watch?v=_dijGeMo8s4
He mentioned it again during the epilogue, "What Did We Learn on the Show Tonight, Craig?"