fact guaranteed
A 'fact guaranteed' is when someone says something so surely it sounds like it’s already happened. Like they’ve already won, you’ve already lost, and there’s no coming back.
'You're gonna get a D,' he said, like he already handed me the report card.
'I’m gonna be the best at this game,' she said, like she’d already beaten everyone else.
'You’re gonna eat all that cake,' my mom said, like she had a cake contract with my stomach.