We've all seen videos lately of singers doing "flash mob" performances in train stations, shopping malls, etc. I've no problem with those venues, as there is nothing inherently sacred about those surroundings.
However, there are some teachers at St Mary Catholic Church in Sioux Falls who, not appreciating the gravity of Lent and Ash Wednesday, goaded their pupils into doing a "flash mob" stunt during Ash Wednesday Mass. Read this article and watch the video contained therein. As you read how these teachers wax lyrical about this stunt, you may think such blathering to be almost as insipid as the thinking that instigated their liturgical abuse.
What was also abused, in the name of "art", were these children. They were ill-served by those teachers as they learned that they can do goofy stuff and glom all sorts of attention - attention that should be directed soley to Our Lord.