Oh, Kelly. Douchebags are curses, but is the word douchebag itself a curse? Not so much. In fact, "douchebag" should be used as often as necessary, i.e. a lot.
Here's the vid with Kelly's response. She's one of many celebrities who were asked by Britain's Channel 4 to reveal their fave cuss words. Warning: This vid is NSFW. Unlike Kelly, most celebs picked the naughtiest of the nastiest words out there. Prepare your sensibilities.