(in response to a question) I don't know!

Used other than figuratively or idiomatically: see don't, tell, me. / (idiomatic) Used to introduce a guess at a fact or situation, as if forestalling the other speaker's utterance.

(colloquial) Introduces a compromise or arrangement where the interlocutor has some benefit or advantage.

plural of tell-tale compass

(sarcastic) Said to someone who has ill-conceived, false beliefs.

(idiomatic) Alternative form of time will tell

Synonym of to be honest

Advice to writers: convey an impression by the way that events are described in the narrative, and not by explicitly stating facts.

(idiomatic, sarcasm) Used in response to an assertion that one is already fully aware of.

Alternative form of I tell a lie