Some people actually have a condition that causes this. There are places you can go to learn more on this.
It has something to do with the esophigus and it's mechanism to block off the wind pipe.
To learn more this may help you:
http://www.gagreport.com/bizarrenews_10_5_05_got_sperm.htm
It has something to do with the esophigus and it's mechanism to block off the wind pipe.
To learn more this may help you:
http://www.gagreport.com/bizarrenews_10_5_05_got_sperm.htm