The act of excreting prior to taking a shower. It is the opposite of doing a show-shi.
Person 1: Dude, I just did a shi-show, I feel like a million bucks.
Person 2: You did what?
Person 1: A shi-show: I took an amazing shit and then jumped in the shower. Now I just feel light and clean!
The act of having showered and subsequently realize that you must excrete. It is the opposite of doing a shi-show.
Person 1: Fuck man! I just did a show-shi!
Person 2: Did you not know you had to take a shit?
Person 1: No, I didn't feel it coming until I stepped out of the shower.