HAHA When I read the title of this post I thought wth? How could someone make an app that does that think it was a good idea. Reminds me of the stories from my old communication days hearing people used to warm their food in front of microwave radomes and then got radiation poisoning. You phone doesn't put out enough noise to do that but it can warm the phone.
I try to shut off all the secondary radios if I am not using them .. gps, 4g, wifi, etc. That seems to help