On-air eye roll equivalents

One difficult aspect of being a radio talk show host must be refraining from asking a caller whose opinion on a topic is heavily flawed, "Are you out of your mind?"  The universal ways of wrapping up a call with an out-to-lunch listener are usually "You're entitled to your opinion, I guess," or "That's a subject of much debate."  When a host says that, I always wonder if (s)he's thinking, "I could've been a forest ranger," as "WKRP In Cincinnati" program director Andy Travis did.