peach on someone 告密
inform on someone 举报
A: Did you hear? He peached on us!
A：你听说了吗？他告发了我们！
B: I can't believe he peached to the boss.
B：我不敢相信他向老板告密了。
1) 告密；揭发
2) 举报某人
3) 背叛
1. 告密，揭发
verb (past tense/past participle)
1. To have informed against someone or betrayed someone.
Synonym: informed, betrayed, snitched