the unspoken prayer request

I never really understood why they do this, churches I mean. Typically, it will go something like this: pastor asks for any prayer requests, people share theirs and then the pastor says, "do we have any unvoiced or unspoken requests today?" and it seems like half of the people in church raise thier hands, then the pastor prays. What I don't get is why he doesn't just pray for any unspoken prayer requests anyway. I always kinda felt like those people who raise their hands were trying to communicate just how hardcore thier prayer request really was,"My prayer request is to awesome to audibly say, if I did then your head would probably explode". They probably don't actually think that, but it's the impression that I sometimes get, which is probably bad, and god will probably smite me with a bolt of firelightning,(which is a lethal combo of both fire and lightning) and then my family will be forced to voice an unspoken prayer request for my pagan soul that was smited with said firelightning, unvoiced of course because the pastors head would probably explode. Proof that God has not only a sense of humor but also a thick coat of irony as well.