Why does Mahoney obey?

Mahoney has no ambition about being a cop. He's only interested in himself and his freedom. He wants to be kicked out. He is basically a hoodlom in a uniform.

Mahoney rips his pants and tells Harris, 'I'll be back later in the day'.

Harris tells Mahoney to be back in five minutes, Mahoney not only listens to his full, slow scream, but also takes it as something he has to obey.

This is even before he decides to stay near the thighs, so at THIS point, what motivation does he have for obeying Harris?

What is Harris going to do, slap him? Kick him out (which is what Mahoney wants)?

Say Mahoney wouldn't come back until the next day. What would happen? What is the punishment he is fearing?

Also, 'run him some more' - why does he run? Why does he obey again? What would happen if he didn't? Surely even sitting in some lock-up would beat having to run until you throw up and then continuing, right?

Mahoney makes no sense.