block8.js

function sayOwnColor() {
	console.log(this.color);
}

var red = {
	color: 'red',
	sayOwnColor: sayOwnColor
};

var blue = {
	color: 'blue',
	sayOwnColor: sayOwnColor
};

red.sayOwnColor(); // "red"
blue.sayOwnColor(); // "blue" 

red.sayOwnColor.call(blue); // "blue"
blue.sayOwnColor.call(red); // "red"