Don't tell your wife that her dog does not love her.
This one goes out to all of the pet lovers out there. My wife and I argue over who our dog loves more. I say our dog loves my wife more and my wife thinks our dog loves me more.
Well during a playful spat about the dog's relative levels of love for the two of us, I said to her: "No wonder your dog doesn't love you." And what was playful went to sad and hurtful.
While we were still joking about it, that comment sucked some of the fun out of it. Not a huge deal but worth noting.