Exodus 20:7 Thou shalt not take the name of the Lord thy God in vain: for the Lord will not hold him guiltless that shall take the name of the Lord his God in vain.
Today I watched a group of young school girls fawning over a cute little puppy. One of the girls kept saying over and over, "Oh my God!" She was probably about ten years old, and like most children her age, probably doesn't think twice about using God's holy name as a casual and careless expression in conversation that amounts to little more than a punctuation mark for their speech.
I doubt most people who use God's name so casually have ever considered the majesty of God, or realize that they are calling upon God to fulfill a vain, human purpose. When I hear frivolous use of God's name, I say in my mind, "Blessed be His holy name." A friend of mine has a different approach, though. She says she considers the expression, "Oh, my God" an unfinished prayer, and she adds the words "Convert me" as a petition pleading for their conversion. She tells me that someone she knows stopped using God's name in casual conversation after awhile, which she attributes to this prayer on their behalf.
Whichever approach or prayer you use, it is important to make retribution to God when we witness the misuse of His holy name. Jesus Himself gave us the Golden Arrow prayer as a means of making reparation for blasphemy:
May the most holy, most sacred, most adorable, most mysterious
and unutterable Name of God be always praised, blessed,
loved, adored and glorified, in heaven, on earth and under the earth,by all the creatures of God, and by the Sacred Heart of Our Lord Jesus Christ in the most holy Sacrament of the altar.