So DS2 has just announced he's cooking at school tomorrow. (He likes to spring these kind of surprises on me, in fact he's given me more notice than usual)
It's pea and ham risotto. I don't have the risotto rice, the bacon, the peas or the onion.
As a dutiful parent I'd normally whinge a bit, tell him off and send him to the shops for the ingredients.
However tomorrow I'm working until 9.15pm, so I've already prepared dinner. DH doesn't get home until late, DS1 will be looking after DS2&3 and serving up the meal to them. So the risotto thing will not get eaten, and also erm, the chances of it being edible anyway are minimal as his talents lie elsewhere 
So AIBU to send a note with some sort of excuse?
I'm not normally a slack parent but I'm reluctant to part with money to pay for food that will go to waste.