So earlier I'm walkin to the park with my twin nieces and they both start laughing and squatting so…

So earlier I'm walkin to the park with my twin nieces and they both start laughing and squatting so I asked them do you have to potty ?they say no I repeatedly ask them of thy have to go and they keep saying no . As son as we reach the park they run to me and one of them says all happily "i pooped my pants " and her sister starts laughing and goes "me too, me too " lol WHY? 😐😐😒