Jip and Janneke (Dutch: Jip en Janneke) is a series of children's books in the Netherlands, written by Annie M. G. Schmidt and illustrated by Fiep Westendorp. The series is known for its simplicity and wit.
In  recent years, Jip and Janneke has become part of an expression in the Netherlands. Jip and Janneke language (Dutch: jip-en-janneketaal) has come to mean "simple language", Layman's terms or Plain English. That means language that is intended to be clear and concise. It attempts to avoid complex vocabulary. It is most often used in the context of politics, when politicians think they need to express their ideas in Jip and Janneke language in order to make the people understand what they are talking about.
You can find these Jip and Janneke images at several places all over the city.