Talkative

She could go on and on about her favorite TV show for hours.

There's some guy at the other end of the bar running off at the mouth about how far he can throw a football.

He is talking a blue streak about his new project.

大嘴巴, 多嘴的人

Don't tell Sarah any secrets; she has a big mouth and can't keep anything confidential.

不要告诉莎拉任何秘密；她大嘴巴，什么秘密都保不住。

During the meeting, our boss talked the hind leg off a donkey, going on tangents and discussing unrelated topics.