fact guaranteed
A 'fact guaranteed' is when someone says something with such certainty that it feels like it’s already in your bones. Like you've already been beaten, you've already lost, and there's no escape.
'You’re gonna fail this test,' he said, like it was already on your report card.
'I’m gonna win this game,' she said, like she already had the trophy in her hand.
'You’re gonna eat that whole cake,' my mom said, like she had a dessert contract with my mouth.