~ Zaungast ~

...a funny, quirky German word for onlooker 

I stopped by my best friend, who also happens to be German to pick up a spray pump. While we were standing on her property discussing insect infestations I noticed someone on her wooden fence. When she turned around I did not even have to point out the face to her, She saw immediately what I saw -  and the sneaky guy was just staring at the ivy and  pretended not to see us;)

I found this explanation online - 
Ok, admit it, have you ever hung around outside the gates at a hot concert you didn't have tickets for. After all, at an open-air event, the sound doesn't stop at the fence. If you have, that would make you a "Zaungast" (or "fence guest"). The word, however, can also be used to refer to onlookers who aren't in the way, but don't actively participate either. On a more serious note, the media, for example, has called the developing world a "Zaungast" to global politics, quietly observing but lacking influence.