OMG: What Does It Really Mean to Use the Lord’s Name in Vain?

I don’t think that the people of Israel were walking around Egypt saying “OMG.” In the tumultuous moments before Moses parted the Red Sea, I cannot imagine that the descendants of Abraham stomped their feet in frustration and flippantly told the Lord to damn anything. I also highly doubt that when Laban promised to give Jacob his daughter Rachel in exchange for seven additional years of service that the soon to be patriarch of the tribe of Israel retorted “say Bible,” as is the practice of some socialites today.

So what gives? If the culture of the day wasn’t to incorporate the Lord’s name into platitudes, then what exactly was the Lord commanding His people not to do in the third commandment?