We all have that one friend. That one who has that biting sense of humor that you don't know if he's joking or if he's telling you the truth. All in all, everyone knows he has a way with words. In fact, they're always dripping with sarcasm. If that person were to create street art, I imagine it would look something like this.
UK-based Mobstr puts up simple sentences that were designed to make you think. Though minimalist in nature, they're often loaded with meaning or, at least, come with a little attitude. (On a side note, these remind me of those hilarious someecards cards.)