Old Question, drawing blank

[fletch_irwin_m]

I can visualize the play, let's see if I can describe it:

Player A is taking the ball out of bounds. Player B reaches over the plane and slaps Player A on the arm.
What is the call? Does it make a difference whether the ball was over the plane? The arm? Neither?
THanks. YOu must have patience with us Rookies!