If there is a second knock it is probably a Jehovah's witness.
I posted that joke on my facebook. I have over 150 non jw friends on facebook and 5 jw friends. the majority of people that commented thought is was funny except for one jw. their comment was "well that 2nd knock has been known to save lives" I didn't say anything for a few days. But then I replied... "Are you saying that if you aren't a jw you will die?" hmmm I wonder if she will get her foot stiuck in her mouth.
Why oh why do I let jws frustrate me so much? I should stop trying to teach the pig to sing.
