1996 :)
Found on Google. 
Paper Towels or Self-Expression?

Found this here: http://calibermag.org/articles/paper-towels-or-liberation/

Found on Imgur, from a UC Berkeley bathroom stall in the physics building.
The best of Cal's bathroom graffiti artists - The Daily Californian

Look! An article about Cal’s bathroom graffiti art, featuring our blog, another bathroom blog, and some original photos… Apparantly, #grout is a bathroom phenomenon… 

Another blog dedicated to the art of Berkeley’s bathrooms!
Seen in bathroom stall in…
From a girls’ bathroom stall in UC Berkeley - Imgur
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