Stuf

Pronounced like „stuff“.
When you say something, which you think makes sense, but someone tells you, that it’s wrong and then you realize, that it’s wrong.

You: „I think, that cheesecake doesn’t have cheese in it. It’s a sweet cake, not a salty one.“
Friend: „It does have cheese in it. It’s just not like a salty gouda cheese.“
You: „...“
You: „Stuf“