He is every council's worst nightmare, but artist Clet Abraham has a serious message to get across. This classically-trained artist, who now lives in Florence, has been sneaking around cities across Europe in the middle of the night and strategically placing stickers on street signs to alter their meanings. And while passers-by may crack a smile when they see the humorous signage, Abraham hopes people will think twice next time they are asked to follow an instruction.He is every council's worst nightmare, but artist Clet Abraham has a serious message to get across. This classically-trained artist, who now lives in Florence, has been sneaking around cities across Europe in the middle of the night and strategically placing stickers on street signs to alter their meanings. And while passers-by may crack a smile when they see the humorous signage, Abraham hopes people will think twice next time they are asked to follow an instruction.