js prototype 巨大疑惑

function FuckYou(){
}
FuckYou.prototype =object_test = {
    name:"John",
 sex:'male',
 getName:function(){
    return this.name;
 }
}
var fuckyou = new FuckYou();
function subFuck(){
     this.sex ='subFemale';
  //FuckYou.call(this);
  subFuck.prototype =fuckyou;
}
subFuck.prototype =fuckyou;
var subObject = new subFuck();
alert(subObject.getName());
alert(subFuck.prototype==FuckYou.prototype);//

// 既然未false，为什么还能引用？