"Humor is always based on a modicum of truth. Have you ever heard a joke about a father-in-law?"

In this quote, Dick Clark is highlighting the reality that humor typically originates from a percentage of truth. He suggests that jokes are frequently based upon real-life situations or experiences, making them relatable and funny. To further stress this point, he postures a rhetorical concern about jokes involving father-in-laws. This is a typical style in comedy, as many individuals can relate to the funny dynamics between a father-in-law and their kid's partner. By using this example, Clark is stressing the concept that humor is typically rooted in truth, making it more relatable and satisfying for audiences.