You shall not misuse the name of the LORD your God, for the LORD will not hold anyone guiltless who misuses his name–Exodus 20:7
In his commentary on the book of Exodus, John Durham writes, “In general terms, this commandment prohibits a lack of seriousness about Yahweh’s Presence in Israel, demonstrated through a pointless, misleading, or even false use of his name.”
In my experience, most of the teaching we do about this commandment focuses on the frivolous exclamations of teenagers–the unfocused “Oh my God” born of excitment or tragedy–or the profane utterances of grown men in carpentry accidents who call upon the Lord to eternally condemn their wretched tools. Both of those are appropriate targets of our sermons, but they are far from the most troubling instances of misusing the name of God. There’s a lot of things that churches, even conservative churches, approve of (or encourage!) that seem to me to violate the intention of this commandment.
Like this:

God Speaks Marriage Counselor billboard
You’ve probably seen this billboard, or one like it. It’s from the “God Speaks” campaign. The whole series was very popular with most of my Christian friends and acquintances. Other signs included:
You think it’s hot here?
-God
Big bang theory, you’ve got to be kidding.
-God
Have you read my #1 best seller? There will be a test.
-God
Don’t make me come down there.
-God
These are wonderful ads, provided that you assume that there actually is no personal, powerful holy God who can and does speak for Himself. If “God” is just the fictional mascot for a massive non-profit organization that provides religious goods and services, then this could be a very effective campaign. But if there is a personal God, then it’s probable that He wouldn’t take kindly to people attributing inane or annoying comments to Him. Especially if a specific prohibition of such friviolity was number three on his list of ten critical words of instruction.
This one is deeply ironic: