Typically, of or relation to a moment when when one's actions make a situation incredibly awkward, to the point of self-injury, but unlikely causing any real or permanent damage. Often related to interactions with the opposite sex.
Origin unknown, but possibly from John Stuart Mill's "On Liberty" and the harm principle, which Wikipedia explains as saying "The harm principle holds that each individual has the right to act as he wants, so long as these actions do not harm others. If the action is self-regarding, that is, if it only directly affects the person undertaking the action, then society has no right to intervene, even if it feels the actor is harming himself."
1. Then I told her we should make out, but didn't kiss her. We stood there staring into each other's eyes, reveling in the Millesian moment. Then she took the subway home, alone.
2. After a brief pause, he pushed a condom across the bar and said "this is my business card". The look of incredulity spread across her face as she realized the Millesian proportions of the social gaffe.
3. "But we don't speak French", she implored. Oblivious, the man continued his Millesian soliloquy in slurred French, fueled by an excess of liquid courage and deficit of common sense.