My twin peed on me on Halloween, How should I get revenge?

Here is the story:

Last Saturday my sister and I were aliens for Halloween. We black out, yada, yada, yada, I wake up in the morning and i'm all wet= confused. I open my eyes and my sister is sleeping next to me. I'm more concerned that I am all wet, I check my undies-dry. I wake up my sis and eventually discover she peed all over my bed and me.

I was angry enough about this but then the next day I went to get a t-shirt out of my drawer and all my shirts are wet. Sniff-sniff, she peed there too. Now I am seriously angry.

Reddit, What is a very creative way I can get this phantom pisser back?