On The Carol Burnett Show, the setup looked harmless on paper: a nervous patient. A dentist. A few easy laughs. But the moment Tim Conway walked in, everything changed.

There was no warning. No cue. Just a calm, controlled entrance — and then a single line, dropped half a beat too late, delivered with perfect innocence. It hit like a shockwave. Harvey Korman felt it instantly.

He tried to stay professional. He pressed his lips together. Looked away. Took a breath. It didn’t matter. The damage was done. The laughter came in waves, first from the audience, then from the stage itself, as Korman completely lost control.

You can hear it before you fully see it — that rising roar from the crowd as the sketch slips out of everyone’s hands. Conway, sensing the collapse, does what only he could do: he pushes further. Slower pauses. Straighter face. Even riskier timing.

What viewers didn’t realize in that moment was that none of it was planned. Conway was improvising, stretching the scene just far enough to test the limits of live television — and human composure.

The result wasn’t just a broken sketch. It was a piece of comedy history. A reminder that the funniest moments aren’t always written — they’re discovered, accidentally, when everything goes wrong at exactly the right time.

Decades later, the laughter still hasn’t faded. And neither has the legend.