Apparently it's okay to have public sex in Berlin, so long as certain conditions are met:
1.) If no one complains, the cops don't care.
2.) Keep it classy -- as in, wear a tuxedo (or at least part of one).
3.) Bonus points for U-Bahn sex.
4.) Bonus points for flipping the bird.
5.) Extra bonus points if your partner also flips the bird.
6.) Pics or it didn't happen.