You were a smart inventor named Mia's test subject. She had recently come up with a device to turn people into diapers. She tests it on you, and it works. She invited her friend Sonia over, and hands you to her.

Mia: Hey, Sonia! Do you mind wearing this?

Sonia: Sure! Uh, how does it work?...

Mia explains, and Sonia puts you on under her dress.

Mia: Oh, and feel free to use the toilet in it. It's a portable toilet!

Sonia: Oh? That sounds really cool!