Looking for some reassurance that I'm not the only one experiencing this sort of behaviour from their 9yr ds! 
He has been getting increasingly silly and rude. Winding up younger brother (who is 6), keeps bickering with him over ridiculous things (e.g. how to pronounce salt), won't stop when asked and then when told off will stomp his feet, start calling out silly words to get a reaction from us.
After time to calm down he is apologetic etc. But it's only a matter of time before it starts again!
Does this sound similar to anyone else?