You have no idea… Definition 1 of 2Pro Tip 1/3Emotional Impact Shows strong feeling about what's unknown or underestimated by the listener. You have no idea how hard I've worked for this. Pro Tip 2/3Expressing Frustration Used when frustrated that someone doesn't understand the full extent of a situation. You have no idea how frustrating this is for me. Pro Tip 3/3Amplifying a Statement Can be used to emphasize the severity or magnitude of a situation. You have no idea how much that meant to me.