A linguistic irritant LXXIX

When it's necessary to convey that I know what I'm talking about, I never use the phrase, "I'll have you know..."  While that's only a minor point in my favor, I think it's considerate.  When has anyone ever said or even thought, "That was a really convincing point (s)he made.  It must have been, because the speaker had me know that it was and was justifiably haughty when telling me?"