You don't have a tumor.
3 seconds sound clip from the When Harry Met Sally... movie soundboard.
You can hear this line at 00:38:02 in the Blu-ray version of the movie.
Quote context
[...]
- Louis, I think this is the beginning of a beautiful friendship.
- Ooh, best last line of a movie ever.
- I'm definitely coming down with something. Probably a 24-hour tumor. They're going around.
- If you're so worried, go see a doctor.
- No, he'll just tell me it's nothing.
[...]