〜ちゃう・〜じゃう: end up doing (casual)

Casual form of 〜てしまう, meaning to finish completely or to do by mistake.

Te-form 〜て → 〜ちゃう, 〜で → 〜じゃう: 食べちゃった, 読んじゃった. Past is ちゃった/じゃった. Shows completion or regret. Used among friends, not in formal writing.