よろこばしちゃう
yorokobashichau

Godan Verb (su)
Godan Verb (u)

The completive aspect (contracted form) - indicates completion or regret of 喜ばす

1. To please (unintentionally); To make happy (unintentionally); To delight (unintentionally); To overdo it (with pleasing)

Completed Action
Colloquial