Urinating in public is quick, easy, and sometimes a very practical solution. But there are nasty consequences as well: you can be fined for doing it, it can damage a building, and it leaves a nasty smell. Chaim Becker has attempted to increase awareness around urinating in public and has come up with a concept for applying a coating to a wall that will respond to urine. It allows people to literally leave their name somewhere or the mark of their favourite football side against the wall of the enemy stadium. Becker has described the different options that Leave your Mark offers in a manual aimed at users such as the government or festival organisers.