Proper Behavior
Eph 5:3,4 But among you there must not be even a hint of sexual immorality, or of any kind of impurity, or of greed, because these are improper for God’s holy people. Nor should there be obscenity, foolish talk or coarse joking, which are out of place, but rather thanksgiving.
Notice the motivation that Paul alludes to here. That is to behave properly because is it the appropriate and right thing to do. This is in line with the previous verses talking about imitating God. If asked as to why you are not involved with sexual immorality or greed or obscenity, you may say, "Because it is not proper for a Christian to do so; it is not appropriate; it is not right because it's not the way God behaves." This is righteous living - to do what is right because it is the right thing to do in the sight of God.