Used with a raising of the arm above the head and showing the palm of your hand sideways to the person you're addressing.

As a way of stopping somebody if what they are saying is of little or no interest to you or you have better things to do - defienately derogatory!
Parent to Juvenile "Stop playing with the PS2 and finish your homework!"

Juvenile (with hand jesture) "Shade Off!"
by Oliver Homan March 26, 2005