If you don't like this sound, this might not be the right sport for you.
http://m.mlb.com/video/v1484714383/minsf-statcast-tracks-vargas-mammoth-471ft-homer/?affiliateId=clubMEGAMENU
I think it's to treat stiffness or mild strains. I see it used often around the leg and groin area where a cramp or stiffness can linger for some time.
Edit: I might have just set myself up for a penis joke.