He was extremely rude to a lot of people, some of whom vowed they would never speak to him again.

Inviting a person out and then expecting them to pay for their own drinks, etc. is considered extremely rude.

I went over to speak to him and he was extremely rude.

In that case, it is considered extremely rude to ask the question anyway.

They are extremely rude and have absolutely no respect for private property.

Where I come from, walking out the way he was trying to was extremely rude.

Shaming or humiliating people in public is considered extremely rude.

The host will not indicate when the visit has been long enough, since it is considered extremely rude.

It is considered extremely rude to just lay the food on the table and expect guests to serve themselves.

"It is extremely rude to keep others from their rest."