My God I have just had a big one. I cannot leave the room without DS2 pulling at DS1 who cannot stand it so he hits back and they scrap.....all the time....every day...unless I'm there.
So when I am with them both, it's lovely. If I have to cook, put washing on, put it away, answer the phone, use the loo etc etc, pure hell breaks loose. EVERY BLARDY TIME!
So, after warning them of my fatigue with this, I left the room to boil a kettle for pasta and bingo....mum, he's hit me, no you hit me...bang, crash, wallop.
Cue me doing the Vicks tantrum [embarrassed]
That stopped them in their tracks.
But it upset them too 
Just got our local NAS support group to host tonight as well. What joy!