A spiel is a lengthy, often glib talk that's intended to persuade or make excuses. Infomercials feature salespeople giving a 30-minute spiel about some product.
Used as a noun or verb, spiel originates from the German word spielen, meaning “to play." It's often somewhat rehearsed and should be greeted with skepticism. Upon turning 16, your child might give you a spiel about why they need a car for their birthday. In a political debate, if your stance doesn't sound original, thoughtful, and earnest, it may just come across as a spiel, leading your audience to think, "Oh, brother, there they go again."