Jane: "Hey Laura, did you end up hooking up with that basketball player?"
Laura: "Yeah. Went up on him."
Jane: "Word. You go girl. Going up (on somebody) is so neo-modern."
The act of defecating in the upper tank of the toilet. When the next person flushes the toilet they get a bowl of beef stew. Should only be used on people who deserve it. Also known as an 'upper decker'