The Art of Battle

I have been reading up.

There are seven manoeuvres of war:- penetration of the centre; envelopment of a single flank; envelopment of both flanks; attack in oblique; feigned retreat; attack from a defensive position and the indirect approach.

Nowhere, but nowhere does it state that in order to achieve your goal (and in this case ownership of the tennis ball) should one render a gentle blow of air up the opponents nostril!

So why, oh why does Joe keep doing it?