you must be (kidding).There is no person in the house.
kid无论是做及物动词还是不及物动词都有开玩笑,取消的意思.
及物动词 vt：
They kidded him about his paunch.
他们取笑他肚子大.
不及物动词 vi:
I was only kidding.
我不过是在开玩笑