How do you deal with back chat and general rudeness

[Tillytoes14]

Hi,
My 8 year old son has become quite rude to me, his dad and his younger brother recently. Typical things he may do, answers back whilst being told not to do something, budging past and not saying excuse me when he's wanting to get past, being sarcastic and generally quite rude towards us and forgetting his pleases's and thank you's, which was something he was always good at remembering.
I'm wondering where my pleasant and polite son has gone, most mornings we spend arguing and he wakes up in the most foulest of moods.
We do have rules at home, if he breaks them we tend to take a certain amount of computer time of him, but, he doesn't seem to care recently and I honestly think he just needs to be removed from the situation (such as being sent to his room) to calm down and reflect on his behaviour, but my husband thinks sending him to his room won't bother him as he can still play/read etc.
Any tips, or words of advice please.
Thanks

[evertonmint]

Watching with interest: my 7yo is similar, particularly rude towards his younger sister.

[Andro]

Would you like to try that again?

If that doesn't work...

Your tone is rude, either apologise or go to your room until you are ready to speak politely.

Finally...(if neither an apology nor self removal are forthcoming)

Conservatory...right now! Stay there until I come to talk to you.
This is the reaction both my dc try to avoid, life goes on without them and they miss outings/TV shows/Skype with their Aussie based grandparents/anything else fun until they back down and apologise. I rarely have to use it but ages 4, 7 and 10 have all required an attitude adjustment.

When either one is rude to the other, a hard look and a reminder that saying xxx in that manner is not acceptable usually yields the desired result - backchat me and I deal with it as any other rudeness

[BlueChampagne]

Do you think there might be anything behind it?

I go with a certain amount of sarcasm, such as "excuse me is the phrase you're looking for", or "and now in a civilised fashion?". Have occasionally used "rude children don't get treats".

DS1 is 7 so I guess I've got it all to come!