Whereas Kumamon is a “yuru kyara” (“laid back character”) I saw one Japanese article that called this sign a “yuru kanban” (“laid back sign”). It mimics a phrase made popular by a couple of comedians to get its “No drunk driving” message across.

http://en.rocketnews24.com/2014/09/28/japanese-buzzwords-and-regional-dialects-keep-kumamoto-drivers-safe-【photos】/