I think '아무렴 그렇지, 그렇고 말고' was a TV show back in the 80s. I'm not sure if it's a common expression beyond that.
I am having trouble getting a handle on what it means. '아무렴 그렇지' seems to be something like 'Of course it's like that...' but I'm not sure about 그렇고 말고. Can someone break it down for me?