How can/could you! Definition 1 of 2Pro Tip 1/3Emotional Charge This phrase often conveys strong emotions like betrayal or hurt feelings. How could you forget our anniversary? Pro Tip 2/3Common Misuse Don't use it for mild annoyances, it's for serious actions. How could you not answer my message for a week? Pro Tip 3/3Conversational Tone It's informal, often used among friends, family, or close relationships. How can you just cancel our plans last minute?