She promised not to tell on him about the secret they shared.
someone
Frequency:
60
%
I can't believe you told on someone who trusted you.
friend
Frequency:
50
%
I would never tell on my friend, no matter what.
lie
Frequency:
45
%
He didn't want to get in trouble, so he decided to tell on the lie.
Idiomatic Expressions for tell on
Phrase: tell on oneself
Meaning: to unintentionally reveal something about oneself, often something incriminating
Usage: He told on himself when he accidentally mentioned being at the party he wasn't supposed to attend.