Enjoying a lazy day in Golden Oaks Libarary, Twilight Sparkle finds it rather annoying to interrupt her recreational reading in order to relieve herself. She decides it would be much more convenient to use her underwear as her toilet, and then worry about clean-up later.

WARNING: SOFTCORE-SCAT ERTOTICISM. MORE SPECIFICALLY, PANTY-POOPING
I know it's pointless to say, because people love downvoting stuff they don't like, but if this is not something you enjoy, please do not read any further. It's not hard to click the back button and go find something you actually enjoy reading.