Here's why:
* Sign language is not universal: Different sign languages have different signs and meanings. What might mean one thing in American Sign Language (ASL) could mean something completely different in British Sign Language (BSL).
* Sign language is contextual: The meaning of a sign depends on the surrounding context. A sign can have different meanings depending on the facial expressions, body language, and other signs used with it.
* Thumb on nose isn't a recognized sign: There isn't a recognized sign in most sign languages that involves putting your thumb on your nose.
Possible scenarios:
* It could be a personal gesture: Some people may use their thumb on their nose as a personal habit or gesture.
* It could be a misunderstanding: They may be mimicking a sign they saw, but are getting it wrong.
* It could be a part of a larger sign: If they are using their thumb on their nose in combination with other movements, it could be a part of a larger sign.
To understand the meaning, you would need to:
1. Know which sign language they are using: This will help you understand the basic grammar and structure of the language.
2. Consider the context: Pay attention to the person's facial expressions, body language, and any other signs they use.
3. Ask for clarification: If you're unsure, the best way to understand is to ask the person directly.
Remember, sign language is a complex and rich language. If you want to learn more, find a local sign language class or resources online.