Why can't I take pictures right away sometimes with my Nikon d7000?

Don't get me wrong I love this camera, and it takes beautiful pictures. But sometimes when I try to take a shot, it won't let me take it. I end up pressing the shutter a million times and the people I try to take pictures of lose the moment. I'm not stupid the camera is on, I assume that it won't let me take a shot if the picture isn't focused. How do I turn this off by not going into manual focus? I want it to take the shot when I press the shutter regardless if it's focused or not but still be able to focus when I give it the opportunity to. Can this be done?

Focus depends upon contrast to lock. If you are shooting in low light you may well have an issue with the focus locking on because there's nothing for it to lock to. Weaker lenses will also have a hard time focusing.
How do you avoid it? Use ample light. Use professional grade lenses. Make sure you are using one single focus point and locking it onto something that is definitely contrasting enough for the camera to "see." Otherwise? It's a fact of life and the only other way to get around it is to manually focus.