来年の事を言えば鬼が笑う
(Rainen no koto wo ieba oni ga warau; “Oni laugh when you talk about next year”)

Definition:

Nobody can accurately predict the future, so there’s no use in trying to say what’s going to be happening next year. People who try are being so ridiculous that even supernatural beings will take notice and make fun of them. This saying is generally used to poke fun at people who talk thoughtlessly about what the future is going to be like.

Breakdown:

We’ve got a couple clauses here. The first begins with the noun 来年 (rainen), “next year.” (Literally “the coming year.”) This is linked by the associative particle の (no) to the noun 事 (koto), “thing,” which in this case serves a function similar to “the matter of” or simply “about.” The final verb of the first clause is 言う (iu), “to say,” in conditional form, and the particle を (wo) marks the preceding noun phrase as its direct object.

The second clause is a simple subject-verb arrangement. The noun is 鬼 (oni), a humanoid monster whose name is variously translated as “demon” or “ogre,” but is perhaps often best left as-is. This noun is marked as the subject by the particle が (ga). And the verb is 笑う (warau), “to smile” or “to laugh,” in sentence-final form.

Notes:

This is the ら entry of the Kyoto iroha karuta set.

Another version of the same saying replaces 来年 with 明日 (asu), “tomorrow.” Other variants simply use the alternate conditional structure 言うと in place of 言えば or elide の事. Finally, a couple versions replace the laughing oni with birds or even with a mouse on the ceiling.

Example sentence:

「計画を立てるのはいいけど、必ず予想通りに成し遂げられるなどと思い込むな。来年の事を言えば鬼が笑うぞ」

(“Keikaku wo tateru no wa ii kedo, kanarazu yosou doori ni nashitogerareru nado to omoikomu na. Rainen no koto wo ieba oni ga warau zo.”)

[“It’s good to make plans, but don’t fool yourself into thinking that you’re definitely going to be able to carry them out exactly as planned. ‘When you talk about next year, oni laugh at you!’”]