I had one like this a few weeks ago, I sneaked into the female loos at a service station there were 4 cubicles but 2 were out of use I went into one to open the sanitary box to look for goodies and 2 females came in one went into the other available cubicle and had a huge pee while the other chatted to her in polish I think, then they swapped and her mate had a big pee and a poo then I heard the sticky pad being pulled from her panties and a plastic bag open then the sanitary box open and close washed her hands and off they went I waited a few seconds to hear if anyone else had come in then rushed to find the treasure… still warm!
I didn’t take the pad as I was searching for sticky grooly panties but was out of luck