～てしまう / ちゃう

About

Attach the auxiliary verb しまう ("to finish; complete") to a て form verb to form the ～てしまう pattern.

E.g. ごめん！マイクのピザ、全部ぜんぶ食たべてしまった！ "Sorry! I ate all of your pizza Mike!"

～てしまう has four main usages: for regrettable/unfortunate actions, for accidental/unintentional actions, for volitional statements of completion, and for "screw it" type statements.

The casual form of ～てしまう is ～ちゃう (or ～じゃう for ～でしまう).

E.g. 食たべてしまう → 食たべちゃう

E.g. 飲のんでしまう → 飲のんじゃう

Summary

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  The ～てしまう pattern is used for regrettable/unfortunate actions, accidental/unintentional actions, volitional statements of completion, and "screw it" type statements

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  The casual form of ～てしまう is ～ちゃう or ～じゃう