Chess Knight Move

Every night, after dinner, a man took off for the local tavern. He spent the whole evening there, and arrived home very drunk around midnight each night.
He always had trouble getting his key into the keyhole and getting the door opened. His wife, waiting up for him, would go to the door and let him in. Then she would proceed to yell and scream at him, for his constant nights out, and coming home in a drunken state. But, Harry continued his nightly routine.
One day, the wife was talking to a friend about her husband's behavior, and was particularly distraught by it all.
The friend listened to her, and then said, "Why don't you treat him a little differently, when he comes home? Instead of berating him, why don't you give him some loving words, and welcome him home with a kiss? He then might change his ways."
The wife thought that might be a good idea.
That night, Harry took off again, after dinner. And, about midnight, he arrived home, in his usual condition.
His wife heard him at the door, and quickly went to it, and opened the door, and let Harry in.
This time, instead of berating him, as she had always done, she took his arm, and led him into the living room. She sat him down in an easy chair, put his feet up on the ottoman and took his shoes off. Then she went behind him, and started to cuddle him a little. After a little while, she said to him, "It's pretty late, dear. I think we had better go upstairs to bed, now, don't you think?"
At that, Harry replied, in his inebriated state, "I guess we might as well. I'll be getting in trouble with the stupid wife when I get home anyway!"