"I'm willing to do whatever it takes to make things better. Please help, Tanya." You know that Tanya cares deeply about her friend, and after a brief moment she smiles and starts to move around the room. Already, she seems to have a plan.
"The way I see it, you have no real option except to level the playing field. Sarah is embarrassed at what you saw. You need to make sure you embarrass yourself as well so that she feels like things are equal again." There seems to be a twinkle in Tanya's eye as she explains this.
"Um...okay. What did you have in mind?" There are some questions that are better left unasked, but there is no option here.
"Well, there are only two things I can think of that would make things even. First, you could wear a diaper so that you know what Sarah is going through. It would not be pleasant, but at least she would be able to get over being upset. The other option is to let me dress you up in my old clothes. We could make you up to look like a little girl. That would certainly embarrass you as much as Sarah is right now. What do you think?" Tanya is waiting impatiently, and it seems like she is a little too excited about the opportunity to humiliate you. You are not sure what the best thing to do would be.