A person who frequently attacks others in speech or writing, but who poses no intellectual threat whatsoever. The motivation of this type of person can usually be accurately construed as a desire to be obnoxious and offensive.\r\n\r\nOrigin: The phrase "porch dog" is used to refer to dogs that sit on front porches and bark (vigorously and fruitlessly) at passersby, but who pose no physical threat.\n> Yeah, that guy has a scathing response to just about everyone who posts in this forum. He's a real porch dog.\n