Place it midway through a short edit, right after the visual mishap appears and before the subject reacts. Follow it with a record scratch or a shocked gasp effect, then let the original scene continue without another joke sound competing.
Über diesen Sound
A very brief voice clip of Peter Griffin saying your balls are showing in a blunt, deadpan tone, lasting just a fraction of a second. It feels crude, awkward and instantly funny, like an embarrassing problem being announced as a helpful warning. The line comes from Family Guy, the animated sitcom centred on Peter Griffin.