Did you ever graffiti public bathroom stall walls?
I write mathstuffs, like explanations about the GCF algorithm, the Mandelbrot Set, Friedman Numbers, Fermat's Last Theorem, and other stuffs. Given most graffiti gets removed within three days at my school, and mine's lasted weeks, the school doesn't seem to care. I also assume some people might find it strange enough to share it on social media, so I add little hashtags such as #mathgraffiti and such. To freak people out further, I also add "mmm dis stuff is real smexxxy. Nothing wrong in mathematical fétíśhíśḿ!" and such xD