You couldn't? There's nothing to it. It's just a trick.
5 seconds sound clip from the The Seven Year Itch (1952) movie soundboard.
You can hear this line at 00:41:35 in the Blu-ray version of the movie.
Quote context
[...]
- Oh, I'm 39 or I will be in August. At the moment, I'm still only 38.
- 38? I was 22 day before yesterday. I didn't do anything about it though. I didn't even tell anyone.
- You couldn't? There's nothing to it. It's just a trick.
- You think you could get it open?
- Do you have champagne glasses?
- Good! We'll have a wonderful time. The man says it's very good champagne.
- Shall I bring the potato chips too?
- Sure. Let's shoot the works.
- Okay.
- Honorable mention, U.S. Camera... U.S. Camera.
[...]