Ah, well, Hawk Moth can create villains via using their anger and whatnot, with the help of an Akuma, basically an evil butterfly he can use to grant his minions abilities, in order to get the Miraculouses. The idea was that one Akumatized villain was a disgruntled babysitter, who, after firing a blast of energy at Ladybug, who finds the wasit area of her costume is now a diaper. She becomes a TB not long after, as a way of stress relief. Or maybe she already was one.
Intro
https://www.youtube.com/watch?v=okjPVHJetZw