"For lack of a better term, they've labeled me a sex symbol. It's flattering and it should happen to every bald, overweight guy"

Dennis Franz is making a joke about how he has been identified a sex object, regardless of not fitting the conventional picture of a sex object. He is bald, obese, and not conventionally appealing, yet he has still been labeled a sex symbol. He is recommending that everybody ought to be labeled a sex object, regardless of their physical look. He is making a point that appeal is subjective which everybody ought to be appreciated for their distinct qualities. He is also poking fun at the idea that there is a certain type of individual who is considered appealing, which this type of person must be the only one labeled a sex symbol. He is suggesting that appeal is in the eye of the beholder and that everybody ought to be valued for their unique qualities.