Google AdSense, one of the most popular Online Advertise Networks, uses a mix of two techniques to deliver ads: contextual ads and behavioral ads, but it is not clear when or how much of the both they actually use. In this work, we raise several concerns regarding behavioral ads. End-users have very little control: once behavioral ads are allowed (which is the default setting), it is hard to predict what part about a user's past interests they will reveal. Our goal in this work is to understand and quantify the loss of online privacy through behavioral advertising.