The courtyard of the Franz Kafka Museum has a sculpture by David Černý called Proudy (Streams). It's two bronze statues peeing into a basin shaped like the Czech Republic. Their hips and penises move to direct the water jet. It's said you can text your name to a number (it's displayed next to the sculpture) and the guys will pee your name. Sadly, I didn't test it. The artist is also credited with the giant babies that appear to crawl on the Prague TV Tower.
