I reminds me of a humourous children (also appreciated by some adults) tv show on Norwegian TV, "Brødrene Dal" ("The valley brothers"). In one episode there was this portal which if you went trough made everything backwards (returning to normal if you went through it again). One of the protagonists got stuck on the "other" side, and responded by yelling "!!!NAAF" ("!!KCUF"). I still laugh whenever I think of it.