Went and brought the wrong textbook with 〜ちゃう

Grammar Explanation: Doing completely or ending up doing with 〜てしまう and 〜ちゃう

Mina is startled to learn that today is Friday.

ミナ:: 「どうしよう！！木曜日(もくようび)の教科書(きょうかしょ)持(も)ってきちゃったよ！」; “What'll I do?! I ended up bringing my textbook for Thursday!”; Literal: “What should I do!! I ended up bringing Thursday's textbook!”
ユカリ:: 「相(あい)変(か)わらずドジねー。」; “You're such a klutz, as usual.”

Key Points

1持(も)ってきちゃった = ended up bringing

持(も)ってきちゃった is casual speech for 持(も)ってきてしまった, showing that Mina has done something unfortunate and now has to deal with the result.

2Breaking down 持(も)ってくる

3よ marks Mina’s alarm

The sentence-ending よ pushes the information outward, matching Mina blurting out the problem to Yukari and Sanae.
Together with どうしよう, it makes the line sound panicked rather than calmly explanatory.

教科書 (Textbook)

教科書(きょうかしょ) means a textbook. It is a book prepared for a specific school subject or branch of instruction.

木曜日 (Thursday)

木曜日(もくようび) refers to Thursday, the fourth day of the week, falling between Wednesday and Friday.