Mocken is a german synonyme for Cocaine, most used by dealers.
Ey digga, hast du die 5g Mocken bei?
jo dude!
You would use the term mocken when someone is clearly winning the arguement. It is just to show them that you don't give a shit what they think. And it will really piss them
Off after a while.
You:Dude the sky is red
Them:No it's not
You:Mocken