‘Damian,’ I said, ‘Is this your milk in the fridge?’

‘Yes,’ he said.

‘It’ll be overdue tomorrow… If you don’t want it, I can make yoghurt out of it.’

Richard, who was also in the kitchen, perked up in interest. He asked, ‘How do you make yoghurt?’

I began to explain. ‘Well, you put yoghurt in it…’ Before I could finish, Richard and Damian were laughing hysterically.

‘What?’ I hadn’t even said anything funny.

‘You put yoghurt into it!’ they chortled. ‘How do you make yoghurt? You put yoghurt into it!’

‘Well, you have to, because…’ But they were laughing too loudly for me to justify my apparently inane statement.

‘It grows!’ I cried, trying to shout over them. ‘It’s alive! You need to grow the yoghurt!’

I don’t think they heard me.