Place it at the very end of a bit as the final reaction, after the original comment plays clean on its own. Keep it as the last element in the sequence so the conversation, caption, or on-screen text does all the setup work first.
About this sound
This is Michael Scott saying 'That's what she said' in a short, smug one-liner delivered by Steve Carell. The tone is proudly immature and instantly knowing, turning an ordinary remark into an awkward, funny punchline. It comes from the American version of The Office, where the line became Scott's defining catchphrase.