I tell you | I can tell you | I’m telling youidiomPart oftellI tell you | I can tell you | I’m telling youI tell you | I can tell you | I’m telling you — idiomidiom1. Used to emphasize what you are saying, especially when it is surprising or hard 1.idiomDefinitionUsed to emphasize what you are saying, especially when it is surprising or hard to believe.ExampleIt isn't cheap, I can tell you!I'm telling you, that's exactly what she said.