Oh, Winky. I sympathise. My DS (five later this week) could be your son. He doesn't flare up every day, but a few times a week, yes, and they are SUCH big, out-of-control outbursts that I'm a bit at a loss as to what to do. So I do feel for you.
NotSoRampant, your post about your DS lifting things up in the flooring shop and declaring his strength made me smile. My DS does the same thing - keeps going on about his muscles getting bigger. There is a testosterone surge that spans this age, I think (well, Steve Biddulph thinks so), which explains the hike in aggression, rage and look-how-strong-I-am stuff. I blimmin' hope this is the explanation for some of DS's behaviour!
I'd second the recommendation for the 'How To Talk ...' book. However, I'm not finding it a panacea. It got me through last week without a blip. Then DS lost it Saturday morning when he remembered I would be going out for a few hours in the afternoon - shouting in my face about not wanting me to go, and if I did go, he'd punch me in the face. (I never speak to him like this BTW - again, I am hoping it's this testosterone thing ... he's a huge boy for his age, and grows like a weed ... so maybe has a lot of testosterone ... I'm clinging to this one!) He told me he didn't love me, my parents, my family, himself, that we're all rubbish - all the while with my learning disabled sister in earshot, who then burst into tears. I tried to stay calm and handle it a la 'How To Talk ...' but you know what, it just went on and on, and I had to restrain him because he was bashing me/stuff around him. We were both a bit shell-shocked after that, TBH, and for all my compassion and acknowledgement of his big, angry feelings, I felt like a well-worn doormat, TBH.
Another one of these episodes started building on Sunday morning. I find it so disrespectful, and didn't want to feel like a doormat again, and so I held him firmly by the shoulders, and borderline shouted at very close range, that he was being incredibly rude and disrespectful, and that I had had enough. I would not tolerate it anymore. (OK, maybe not my best line ...) But it worked. How can I teach him to respect me if I don't respect myself? He was as nice as pie afterwards and, touch wood, has been lovely since. He's lovely company most of the time - funny, interesting, sweet, bright - but it's as though he's a little volcano which erupts every few days.
He's a fan of all things poo, wee, bum, farts, etc, too.
I'm so grateful DS has become a cycling fan since he jettisoned his stabilisers at Easter. That's our energy outlet sorted until it gets frosty again.
Grateful for this thread, too. Don't feel so much now like I'm doing a shit job, and that this is just how it will be sometimes/for a while. Hope you're all finding ways to handle this phase.