Shumiss is where you take a bath and you relax so much that you release all of your bodily fluids in a bath so it's a shit, cum and pissmix. Pronounced Shum-iss.
ahh Brad, did you see did you see Kathy's instagram picks of The Shumiss mix in her bath last night? yeh bro it was savage!
Shumissimo is an invented word derived from the Albanian word "shume", which means "so much", combined with the Italian suffix "-issimo" to emphasize the meaning