Because he has just drawn all over the lounge wall with a biro.
This is the second time in a week. Last time it was with a permanent marker, and he got told off, and told it was not allowed.
Tonight whilst I was tidying the kitchen, he did it again. I sent him to the naughty step when he told me what he'd done (not in a repentant way, just matter-of-factly). Then when he came back into the lounge, he pointed out a whole different area he'd drawn on as well.
We live in a Navy house, so will have to repaint (I can't get it off, and scrubbing just removes the paint and looks even worse), or be billed for the damage.
I have told him the the car will go back to the shop.
Reasonable response? He's 3 (4 in April).