I saw this on the side of a newspaper vending machine (Seattle Times). I'm having trouble understanding what the owner means by "my anonymity that your laws can't hold!" Maybe it's a forced rhyme and that's why it doesn't make much sense. With "I mock thoughts" I wonder if it means that this post-up is mocking other stickers with real thoughts on them, or if this sticker is supposed to be like a meta sticker - as in all stickers mock thoughts. I prefer to think the former is the case. Either way, it's pretty nihilistic. I like the head with the empty balloon. I wonder if the tag on the right came with the sticker or if that was added later.
"mock" can be taken two ways. You can mock thoughts by ridiculing or challenging them. You can also mock thoughts in the sense of imitating them. The double message is an interesting one, whether on purpose or not. The sticker owner creates and purveys thoughts (by mocking them up), while at the same time questioning public perception (by mocking social thoughts/ideas).
"anonymity that your laws can't hold" ... Is the author suggesting that "our" laws can't protect her anonymity, or is she stating that our laws won't accept her anonymity? Maybe a better rhyme could have been something like "my identity, from your laws I withhold" or "my anonymity your laws would control."