When I fart, Liquid comes out. Almost like I am peeing from my butt. Why?

It sounds like. Loose stool/diarrhea along with some gas. This can happen for any number of reasons but most commonly infectious processes or irritation of the intestinal tract from a toxin in something you ate. Try to focus on a bland diet like the BRAT diet(Bananas, Rice, Applesauce and Toast) as they are easy foods to digest for the next day or so. Seek help if this persists or you have abdominal pain.