So Guy's why do you have to whistle at girls who walk by?

Seriously Guys (Guys only) humor me for a moment. Why do you embarr us girls? Seriously what do you think that you will gain by whistling and saying vulgar things. I really don't get it! Seriously, how do you want a girl to respond because im pretty sure the reaction that you wish will happen never will, but for the time being i just want to know why you have to act so rudely towards us girls.