also: じまう
auxiliary verb, godan verb (-u)
Expresses that an action is carried out thoroughly or to completion. Often carries a nuance of finality or regret depending on context.
宿題を全部やっちまった。
I completely finished all my homework.
彼は先に行っちまったよ。
He's already gone on ahead.
auxiliary verb, godan verb (-u)
do accidentally; do without meaning to; happen to do
Indicates an unintended or regrettable action. Common in casual regretful statements.
電車に傘を忘れちまった。
I accidentally left my umbrella on the train.
笑っちゃいけないと思ったけど、笑っちまった。
I knew I shouldn't laugh, but I ended up laughing.