The Street Art by Mentalgassi

Berlin-based street art crew Mentalgassi are well-known for their oversized paste-ups, showing expressive, crazy faces of their friends. In the past, they also experimented with concrete, stickers and X-films, self-sticking color transparencies, for the ticket validators on the Berlin subway-stations.
They created so-called “Flip-Images”, large-scale image-installations which make it possible for the public to see different images from different perspectives.
One of their slogans is “Mentalgassi create street art to open your eyes…”, which describes their doings in a great way, because their artworks often let people be aware of their surrounding and the street equipment they would never notice…

(via urbanartcore.eu)