Place it at the end of the joke as the final reaction beat, then let a short dramatic sting underline the pause that follows. For that second beat, use Law & Order Dun Dun, and keep this line as the last spoken moment before the sting.
À propos de ce son
This four-second clip has Hungarian actor Mucsi Zoltán saying Te olyan sötét vagy, meaning you are so dark, in a calm, flat voice that sounds more tired than angry. The restraint makes it feel dry and quietly funny, like a weary comment on a joke that crossed a line. It is credited to Zoltán as a short spoken reaction line.