What did I tell you?
I was completely right in what I told you previously; you should have listened to or believed me. What did I tell you? I knew there was no way that deal could be legitimate. What did I tell you—just one night of studying, and I completely aced the test!
what did I ˈtell you?
(also I ˈtold you so) used for telling somebody who did not listen to your warnings or take your advice that they were wrong and you were right: ‘I’ve got terrible stomach-ache.’ ‘What did I tell you? You should never have drunk the tap water.’‘She didn’t like the present.’ ‘I told you so. I knew she didn’t like perfume.’