GRAMMAR
〜ちゃ（じゃ）
shortcut for ては・では
Explanation
NOTE
ちゃ is a casual contraction of ては. When the て-form ends in て, it becomes ちゃ. When it ends in で, it becomes じゃ.
NOTE
This is very common in spoken Japanese. For example, 食べては becomes 食べちゃ, and 飲んでは becomes 飲んじゃ. It is often used with いけない or だめ to express must not.
STRUCTURE
Vてちゃ / [V][~~で~~]じゃ
ここで走っちゃだめだよ。
Koko de hashiccha dame da yo.
You must not run here.
お酒を飲んじゃいけない。
Osake wo nonja ikenai.
You must not drink alcohol.
遅れちゃだめ。
Okurecha dame.
You must not be late.
Practice exercises
1
ここで写真を撮っちゃだめだよ。
You must not take photos here.
Answer
ちゃ
2
嘘をついちゃいけない。
You must not lie.
Answer
ちゃ
3
遅れちゃだめだよ。
You must not be late.
Answer
ちゃ
4
ここで食べちゃだめだよ。
You must not eat here.
Answer
食べちゃ
5
ここで遊んじゃいけない。
You must not play here.
Answer
遊んじゃ
6
お酒を飲んじゃだめだよ。
You must not drink alcohol.
Answer
飲んじゃ
7
授業中に居眠りしちゃいけないよ。
You must not doze off during class.
Answer
居眠りしちゃ
8
機密情報を漏らしちゃいけません。
You must not leak confidential information.
Answer
漏らしちゃ