しゃべっちゃう
喋っちゃう
shabecchau

Godan Verb (ru)
Godan Verb (u)

The completive aspect (contracted form) - indicates completion or regret of しゃべる

1. To blurt out; To babble; To say (and regret it); To chatter (and regret it)

Completed Action
Colloquial
Usually Written in Kana