You rude, discourteous egomaniac.

Dear discourteous driver...?

That waiter has been exceedingly discourteous.

I'm sorry. Have I been discourteous?

Well, even though he was slightly discourteous to me recently,

On the contrary. He's rude, disrespectful, self-centered and discourteous.

You might be thieves, but you needn't be discourteous ones.

Even though he was slightly discourteous to me recently,

I don't mean to be discourteous, but I doubt it.

Attempts to raise the issue with those responsible for the cafeteria sometimes elicited discourteous responses.