I have a client who suffers from frequent compulsions to do various things, so far mundane but in theory they could be dangerous. At the minimum they make it difficult for him to integrate socially, and the long-term potential for causing problems is pretty significant.
His mom's solution is for him to isolate himself and pray whenever they come up, which isn't the worst advice in the world but is possibly the least useful advice ever given. Like most prayer it creates the illusion of doing something without actually doing anything, and as a result I can't really create any kind of appropriate replacement behaviors because she's so wedded to him praying away the problem.
Not exactly a petty prayer, I guess.