fast ball
The act of slapping ones friend across the face with a hand that recently resided upon your sack and taint.  Best performed after a night of dancing and drinking.  Caution, execution of a successful fast ball will require a retreat with due haste as the recipient of the fast ball WILL retaliate with extreme violence.  Best executed whilst already running from your victim.
Person 1:  I can't believe you fast balled Eddie!  Didn't you remember he's our ride home?

Person 2: iJust keep running/i