So, let's say that you find yourself on a wildly exciting date with a handsome gentleman and through a course of cocktails and conversations you discover that his sexual proclivities are restricted to topping only. NO VERSATILITY! NO NEGOTIATION. The topic is strictly off limits. If this arrangement is agreeable then by all means proceed but make him pay the check before you leave.
If however, this arrangement is not agreeable then suggest that you go "dutch" on the drinks, then stamp his forehead, "Deco. B. Hole" as a warning to other admirers and patrons that this man's butt hole is purely decorative and nonfunctional.