You're a blabbermouth.

He's a real blabbermouth.

At the beginning of civilization, the crazy man, the shaman, ate grass on the river bank and pulled his hair out. Now today, the same madman blabbers on his cellphone about crypto-currency, buys a scone at Starbucks for $4.35, and his hair falls out on its own.

Tom is a blabbermouth.

I'll tell you what happened. You started blabbering and they figured the whole plot out. We're screwed!

What are you blabbering on about?

I know that Tom is a blabbermouth.

She kept blabbering about how her boyfriend is kind, compassionate, brave, and whatnot.

Nah, I wouldn't say anything to a guy like Tom." "That's right. Why would you say anything to a blabbermouth like him, of all people?"

I know Tom is a blabbermouth.