>>42309219It's something earth pony mares don't talk about because it's embarrassing and usually only happens once before they get rid of underwear for good.
They hear the unicorn and pegasi mares bragging about how turned on their special someponies are by their sexy new underwear.
Earth pony mares that had the experience ruined by bodily functions, give knowing looks to the star eyed inexperienced earth mares. Too embarrassed to warn them but feeling guilty for not.