What does it mean when you call a person thiko?

"Thiko" is not a word in any major language. It's possible you meant a different word, or it could be a slang term or regional expression.

Could you please provide more context? For example:

* What language are you referring to?

* Where did you hear this word used?

* What was the context in which it was used?

With more information, I might be able to help you understand what "Thiko" means.