Something red under the sofa

What's that? John kneels down and reaches under the sofa, closing his hand around something soft. It's fabric, silky, smooth, and small, and now it's caught on something. He pulls and wiggles it gently, trying to dislodge whatever it is, but then jolts, tearing it free as he feels something small and hard thwack against his exposed asshole. He scrambles to his feet and spins around to find his giggling aunt Miriam.

"You take plumber's crack to a hole new level, John." She cackles at her own joke.

John's brain fizzles as it tries to process the joke. Plumber's... Oh, because I'm not naked but I have exposed... Did she just 'coin slot' me? He's still struggling with the thought as his mother enters.

"Oh, good, you found something to cover yourself from the back." His mother frowns. "It's not much but it's better than nothing. Put them on, quick. I think I hear the first arrival and I don't want them thinking I have a son who runs around in the nude at parties like he did when he was small... er, young."

John sees where she's looking and follows her gaze to his hand, which he can now see contains a pair of crimson red panties with a tear in them.