The contagious effect, much like a yawn, of hearing one friend snort their nose, which will usually be followed by a wipe of the nose, that immediately makes the other friend repeat the same actions. Thus, making it obvious to observers that you and your friends have infact been using that white girl, Christina Aguilera.
Mary: "Do you see those two white girl's walking who keep snorting and wiping their noses?"
Jane: "Yeah, why?"
Mary: "They're definitely skeeted out of their minds."
Ashley: "Stop snorting and wiping your nose."
Marissa: "I can't help it, it's the blow!"
Ashley: "Well you're making me coke yawn and its obvious."