How I Met Your Mother, Season 4

Future Ted:
Kids, here's something I wish my dad had told me. The longest pause you will ever experience in your life is the one that follows asking the question...

Ted:
[to Stella] Will you marry me?

Future Ted:
Your brain goes into overdrive, imagining every possible response.

[Flashbacks to every possible response]

Stella:
No.

[Next response]

Stella:
Oh, god no!

[Next response]

Stella:
[bursts into laughter] You want me to marry... No.

[Next response]

Stella:
Awww I'm sorry Ted, I can't. Mark Johnson, the quarterback from the high school football team, already asked me.

Mark Johnson:
What's up, turd?

Ted:
It's TED!

[Back to present time]

Future Ted:
But if you're lucky, she might answer with the single greatest word in the English language...

Stella:
Yes.