ちゃいかん

expression

must not do; shouldn't do

Colloquial contraction of てはいけない. Used in casual speech to forbid an action. Often heard in dialects or informal settings.

• そんなことしちゃいかんよ。

  You mustn't do that.

• ここで騒さわいちゃいかん。

  You must not make noise here.