No, you cannot use regular coffee grounds in a Keurig. The Keurig system requires special K-cups or pods that contain the right amount of coffee grounds for a single serving. If you try to use regular coffee grounds in a K-cup, the water will not be able to penetrate the grounds and you'll end up with a weak, watery cup of coffee. Stick to using K-cups or pods designed specifically for Keurig machines to get the best results.