It's a long story

[drencrom]

How can I say "it's a long story" in Chinese so that people will understand? And please don't literally translate it, I'm after the meaning, which is "It would take too long to explain, you wouldn't understand it anyway, and moreover I don't care to tell you."

[imron]

（这事）说来话长了（or 一言难尽），followed by something like 改天再说吧, to let them know you don't want to talk about it further.

[roddy]

说来话长 is the one that springs to mind. Oh, and 长话短说 (edit: although not if you don't want to talk about it at all)

(shakes fist at Imron)

[skylee]

If it is something that you don't want to talk about, I think you can tell people so directly. Just tell them, 我不想提起這事.

[drencrom]

Well, more in the sense of a polite brush-off combined with the truth that it is indeed too long to tell, combined with the truth that they wouldn't get it anyway.

[imron]

改天再说吧 is a polite brush-off.