No Joke. Brian Koerber on MASHABLE writes,

Brooklyn-based artist and hacker KATSU used his own fecal matter to create a portrait ofFacebook CEO and cofounder Mark Zuckerberg.

The pooptrait, which is currently on display at The Hole in New York City, is a part of KATSU’s first solo exhibition titled “Remember the Future.” The gallery was not immediately available for comment.

I suppose this is nice. I guess..
Actually I think it shows more than anything that the artist has a very healthy digestive system..