the whole chummy locker-room routine

[Coffee Break]

I encountered the expression "the whole chummy locker-room routine", but am struggling to understand it. Could you please let me know what it means? Here is the excerpt:

“You are a friend of Pooh Pasternak’s?” So they knew his old nickname as well. “Friends of Pooh’s are always welcome here.” Handshake, arm around my shoulder, the whole chummy locker-room routine. “He was a good friend of my father’s,” I corrected. “Sort of looks after things.”

- André Aciman, Eight White Nights, First Night

This is a novel published in the United States of America in 2010. It is narrated by a nameless male protagonist. He meets Clara at a Christmas party in Manhattan. Now Hans, the host of the party, is welcoming the protagonist when he said that he was the friend of Pooh, who was also the friend of Hans.

I wonder what the underlined expression means.
I am vaguely guessing that it might mean "a friendly (=chummy) process which takes place in the locker room", but I wonder what "routine" takes place in the locker room.
Probably there might be a cultural thing that I don't know, so I just wanted to ask you.

 

[probus]

You are right about the meaning of chummy. If you think about what a locker room is for, it's not difficult to guess the rest. The people are all of the same sex and they are fully or partially unclothed. Therefore an atmosphere of complete freedom and informality prevails. Off-colour jokes and similar kinds of disinhibited behaviour are to be expected.

 

[emsr2d2]

You'll find that some people (to be honest, mostly men) will excuse their use of offensive language/jokes etc as "locker room banter".

 

[Coffee Break]

@probus and @emsr2d2,

Thank you very much for the explanation.
So "the whole chummy locker-room routine" means "the entirety of the friendly activities usually performed in a locker room"!
And this locker-room banter would usually include offensive/informal language or jokes.

I truly appreciate your help.

 

[Tarheel]

Well, the language might be offensive to some people, but it obviously wouldn't be to those involved.