I might be one of the most polite doctors in the world. You might be surprised to hear that, considering I can sometimes be a bit of a bitch in my online posts and comments, but I promise that in real life, I'm pretty much ridiculously nice to everyone. To a fault, really.
For example, when someone asks me to sign an order and I do it, I then say "thank you" for some reason. If a nurse alerts me to a patient having pain or nausea or whatever, I always end the conversation by saying, "Thank you for letting me know about that." (Sometimes I wonder if it comes off as sarcastic.)
Also, whenever I write an order such as to take out a Foley catheter, I don't just write "D/C Foley," I write "Please D/C Foley." I'm fairly sure I never did that as an intern, but I guess I write fewer orders now or something, so I have time to be polite in my orders.
I guess I sort of learned to do this as a med student, when I had a resident who was really gung ho about writing "please" before his orders. He took it a step further though. After his orders, he would also write "Thank you."