Let's break it down:
* que tienes means "that you have"
* los pantabones is a slang term for legs, but it's not very common and sounds more like a joke or a childish word.
* limpiar means "to clean"
It's likely the speaker meant to say something like:
* "You need to clean your pants" - This is the most likely interpretation, given the combination of words.
* "You have dirty legs" - This could be a more literal interpretation of "pantabones", though it's not the most common way to say it.
To be sure of the intended meaning, you would need more context. Was this spoken jokingly, seriously, to a child, or to an adult?
Let me know if you have any more information about the situation, and I can give you a more precise translation.