しちゃダメ

expression

don't; you can't; must not

Colloquial contraction of してはいけない or してはならない. Used in casual speech to forbid an action, often directed at the listener or as a general rule.

• ここで走はしっちゃダメだよ。

  Don't run here.

• 宿しゅく題だいを忘わすれちゃダメ。

  You mustn't forget your homework.