I tell a lie

don't tell me

Used to introduce a guess at a fact or situation, as if forestalling the other speaker's utterance.

give the lie

To respond to an insult, accusation, or falsehood by saying the offender is lying, particularly in the context of provoking a challenge to a duel.

give the lie to

To reveal or prove (something) to be false; to refute.

I can tell you

Emphasises the truth of a statement.

I can't lie

To be honest, frankly, honestly.

I tell you

Synonym of I can tell you.

I'll tell you

Synonym of I can tell you.

kiss and tell

To betray a confidence by disclosing private information, especially of a sexual nature.