Long - sorry.
DS1 (5yr 10mo) has had an hour long melt down. We were leaving my Grandad's, I gave him fair warning first, then when I went to put his shoes on he kicked me.
I told him not to kick me, I kept my cool, put him in the car while he bit down on my arm, then as I leant across he bit into my back.
As I reversed the car he undid his seat belt, so I got out and went to strap him back in, and he sprinted past me and down the drive.
My Grandad's pearl of wisdom - 'you can't let him do that to you'- I think the implication being that I should've hit him back.
I caught him, put him back in the car and said (again still amazingly calmly) 'If you hurt me again or undo your seat belt we won't watch your cartoon before bed'. Result - still swearing and angry but otherwise a safe drive home.
I opened the car door and off he ran down the road, really fast - have got him home safe and sound after a few minutes.
I'm not a smacker. I'm not a shouter. I do natural / logical consequences, but I can't help but think that if I had lost it with him when he first kicked me (like many other parents I have seen) he would've just bl00dy behaved himself!