Guess correctly the red panties she's wearing

Using your unnatural speed, you take a gander underneath her skirt. She's wearing a set of red, regular panties, made of linen.

You return to your position and flow back into the normal pace of time, declaring with a massive grin what the color, type and material of her underwear are.

The girl's own grin quickly fades away. Her face tells you everything she's thinking. 'That's what I'm wearing, right?' 'How did you know?' 'I will still win this bet if I don't show my underwear.'

She stammers, but then recovers: "You won't get to see my underwear though, so pay up".