The day after
So, everyone out there who's wearing a shirt like this*, or this, there are basically two explanations:
1) You're deliberately making the statement that the flag is just another piece of cloth, and shouldn't be afforded any more respect than any other pattern. This is constitutionally protected (and rightly so), and I approve of anyone choosing to exercising their right to free speech in this way.
2) You think you're being patriotic and respectful, but you've never bothered to go to the effort of finding out what that would actually mean. Ironically, this accidental disrespect seems to be far more common in America than in countries that don't explicitly define how the flag should be treated, and leave it up to the individual's judgement.
*Side note: Someone unfamiliar with WalMart brands might think that the legend "Faded Glory" under the flag is some kind of political comment.