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】/
Japanese buzzwords and regional dialects keep Kumamoto drivers safe 【Photos】
Japan loves its popular trends. They will grab a hold of something that is gathering steam and spread it all over the country. This is especially true in TV. Millions of viewers tune into variety programs to see the current comedy darlings and their catch phrase over and over again. Generally these…