Several hand shakes

One hand shake is a simple greating. Two is still okay if they are at the begining and end of a meeting of some sort. Three is awkward but aceptable. My only issue is when people are so nervus that they keep shakeing your hand throught out the meeting or what not. I have no problem with shakeing someones hand but I have noticed something odd. Most of my friends are female and most of there boy friends when they meet me they get nervous and so on to actualy shaking hands seven or eight times with me. Are they looking for my approval? Are they treating me like there only chance to get layed? Just an odd thing in life that I noticed. ohh well.