cloud cuckoo land
noun (British English)(North American English la-la land)
[uncountable] (informal, disapproving)if you say that somebody is living in cloud cuckoo land, you mean that they do not understand what a situation is really like, but think it is much better than it is 幻想世界；脱离现实的幻境 Anyone who thinks this legislation will be effective is living in cloud cuckoo land. 认为此项立法会行之有效的人都是脱离了现实的人。
Word Originlate 19th cent.: translation of Greek Nephelokokkugia, the name of the city built by the birds in Aristophanes' comedy Birds, from nephelē ‘cloud’ + kokkux ‘cuckoo’.