Taxiied back to the gate and gave the boot to a cranky UAL jumpseater that played nice until we pushed back. As soon as the tug was disconnected, he started bitching about how we (United Express) were stealing jobs from UAL guys and he thought we should all be fired and he didn't give a damn about anybody at our company.

Captain looked him straight in the eye and said with a smile, "Well if you feel that CRJ's don't belong in the United system, then I suppose you can find another United affiliate to take you to work. I certainly am not going to tolerate a hostile attitude from you in my cockpit. As of this moment I consider you a security concern and I don't want you sitting up here." Too bad there wasn't a seat in the cabin...