MyBB Community Forums

The default rep options are:
Positive, Neuteral and Negative.
How can I add a costum reputation option, like Extraordinaire with color purple for example?

You'd need to edit the code. I don't believe it to be possible though.

Instead of adding another option like "Extra Ordinary" rep points, try to raise the positive points, and edit usergroup permissions "Points to Award/Take Away:" to allow that group who can give that Extra Ordinary rep points.