why do only half my christmas lights work

Oh, that's quite a mystery! Let's investigate. First, have you checked to see if the bulbs are burnt out or loose? If that's not the case, we should check the extension cords and outlets for any frayed wires or loose connections. If everything looks okay, there might be a deeper problem. Could it be a short in the wiring? We might need a professional to take a look and diagnose the issue.