That wasn't supposed to happen.
4 seconds sound clip from the Grease (1978) movie soundboard.
You can hear this line at 01:12:46 in the Blu-ray version of the movie.
Quote context
[...]
- Now to the event you've all been waiting for: The National Dance-Off.
- Some lucky guy and gal is gonna go boppin' home with some fantabulous prizes.
- Hey, does everybody here know Marty?
- Okay, cats, throw your mittens around your kittens, and away we go!
- That wasn't supposed to happen.
- Before I was born late one night, my papa said everything's all right.
- The doctor made my ma lay down with her stomach bouncin' all around.
- 'Cause a bebop stork was about to arrive, my mom gave birth to the hand jive.
- I could barely walk when I milked a cow. When I was three I pushed a plow.
[...]