True story (because sometimes truth is funnier than fiction).
In Wales, it's required that road signage be bilingual, English and Welsh. A while back, a sign was required to prohibit heavy trucks from going through a residential area. The English was done first ("No entry for heavy goods vehicles. Residential area only."), and that English was emailed off to a translation department for the Welsh version. The resulting translation ("Nid wyf yn y swyddfa ar hyn o bryd. Anfonwch unrhyw awith i'w gyfieitu.") was put onto the sign below the English version, and the sign was then mounted by the road.
(https://www.dropbox.com/s/kuxhu4trxigzqfj/welsh_sign.jpg?dl=0) (if that doesn't display see https://www.dropbox.com/s/kuxhu4trxigzqfj/welsh_sign.jpg?dl=0 (https://www.dropbox.com/s/kuxhu4trxigzqfj/welsh_sign.jpg?dl=0)
After a short while native Welsh speakers began to let the road department know of a problem. The Welsh part of the sign actually translated to "I am not in the office at the moment. Please send any work to be translated."
The sign was duly removed and re-built.