I had a foster daughter like Calvin. After teaching her for several weeks, dinner would go like this:
“I don’t like tortellini.”
“Yes, you do.”
“Okay.” [takes a bite.] “Hey, this is really good!”
“Told you so.”
My brother was just like that too. If he said he didn’t like something, my mom would point out the falacious fact that he had alriedy tried it and it was his favourite food. He bought it every time.