If you tell your wife she looks fat in those pants, you're stupid and you should apologize.
If she gets mad, and beats you over the head with a sledge hammer because of your comment-- that's not your problem; it's hers. It's indicative of a pre-existing mental problem that just happened to be set off by your stupid comment.
You shouldn't be evaluated, poked, prodded, and studied to determine what caused your inexcusable comment; she should be committed to the nearest asylum for her inability to control her actions, and the disproportionate response.
It's this simple: we're not crazy-- they are. They're the ones with the problem, not us.
There are some that would say...if you said that to your wife, YOU are crazy (or have a death wish)! ;o)