DH and I have retreated to our bedroom because DD refused to go to hers. 
DD (9) is livid that her younger brother is out until 10.30 tonight (at the theatre with a friend and her mum) and she is being asked to go upstairs. Not necessarily to sleep, mind you, just upstairs, so that DH and I can have some peace.
She has refused to budge, because DS1 will have even more to 'show off about' if she goes to bed before him. She is flailing arms and legs and throwing slippers.
I have flounced. Told her to let her brother in when he comes home and turn the lights off when she goes to bed.
It's been about 10 minutes. How long d'you reckon before she cracks?