In the yard of Franz Kafka Museum, you can find quite a provocative sculpture of two peeing men, created by a controversial Czech artist, David Černý. The statues pee numerous quotes and you can even have your own text "written" if you send a text message to a number displayed nearby.
Official Website http://www.davidcerny.cz/EN/piss.html
More Information http://www.prague.eu/en/object/places/1867/statue-peeing-figures
Address Cihelná 2b (Hergetova Cihelna), 118 00 Prague 1, Czech Republic
Coordinates 50°5'17.069" N 14°24'36.809" E