Here are some possibilities based on what it *could* be trying to convey:
* "Eres un loco": This means "You're crazy/a madman" in Spanish. It could be a shortened version of this phrase, though it's unusual.
* "Te has vuelto loco": This means "You've gone crazy/mad" in Spanish. Again, it could be a shortened version, but it's still not a standard phrase.
* "Reta a un loco": This means "Challenge a madman". This is a grammatically correct phrase, but it wouldn't make much sense in the context of "re tas loco".
To get a more accurate answer, you need to provide more context. For example:
* Where did you hear this phrase?
* What was the situation?
* Who said it?
With more information, I might be able to give you a better understanding of what it means.