big mouth

US /ˈbɪɡ ˌmaʊθ/
UK /ˈbɪɡ ˌmaʊθ/
"big mouth" picture
1.

おしゃべり, 口が軽い人

a person who talks too much, especially about things that should be kept secret

:
Don't tell him your secret; he's a real big mouth.
彼に秘密を話さないで。彼は本当におしゃべりだから。
Her brother is such a big mouth, he always spills the beans.
彼女の弟は本当におしゃべりで、いつも秘密を漏らす。