rat on

transitive

(transitive) To tattle, squeal about (someone)

Japanese Meaning

誰かの悪行や秘密を告げ口する、密告する / 誰かの不正行為や不祥事を暴露する

If you rat on your teammates, you'll lose their trust forever.

チームメイトのことをチクると、彼らの信頼を永遠に失うだろう。

Sense（1）

(transitive) To tattle, squeal about (someone)

Who you protecting, you dumb asshole? A stoolie who rats on his own friends?

rats on

（ present singular third-person ）

ratting on

（ participle present ）

ratted on

（ participle past ）

ratted on

（ past ）