No Such Thing

You know what? It just dawned on me moments ago...
If there is no such thing as "truth," that is, if truth is relative to each of us, then there is no such thing as a lie.
I don't happen to believe that because I've been lied to a few too many times, but explain the relativity of truth if indeed it is possible to lie? What is the standard to know a lie from the truth if there is no such thing as the truth?