maggiesensei.com/2010/09/14/request-lesson-%e3%81%a1%e3%82%83%e3%81%86%e3%81%a1%e3%82%83%e3%81%a3%e3%81%9fchau-chatta/
Grammar lesson explaining ちゃう and ちゃった, casual conversational forms of てしまう meaning to finish or complete an action, with conjugation rules and usage examples.