Why are radio signals clearer near the human body?
No one is surprised by the general phenomenon that radio signals get weaker, the further you are from the transmitter. However, most people are surprised at how much the signals will vary within a short distance, locally. 

This effect is called multipath fading, and is caused by multiple reflections of radio waves off walls, cars outside, people etc. At the receiver, the signals can combine to be bigger or smaller than the signal would have been with the multiple reflections. Of course, you don't notice a problem when the signals are bigger. 

A particular issue with FM radio in the 100MHz band is that a typical human is about half a wavelength tall. This means that moving a human around in the region close to a receiver is particularly effective at changing the multipath reflections.