[Dirk makes his unimpressed face. But Fine.]

Balls are ideal because of the possibilities of interaction. Round shape means they move on their own if they hit the ground with momentum. Points of contact are basically the same no matter the direction of the ball and they can be handled with feet or hands easily.

Also, testicles.

[He is looking down on Dave like he is Quietly Fretting but knows he can't do anything else. But still fretting!]