Late night talk show hosts are known for being experts at repartee, or clever conversation, with their celebrity guests.
Repartee comes from the French word repartire, which is a fencing term meaning "an answering thrust with a sword." When you are engaging in repartee, you don't literally stab someone, but you come back with a quick verbal blow. Most of us aren't as quick as we'd like to be. Mark Twain defined repartee as, "something we think of 24 hours too late."