Kyle is convinced Facebook is listening in on his conversations because he'll get ads showing up that is strangely related to conversations he's had within the last few hours. Are they listening in on him? Leo says that would a huge amount of data for a billion and a half users to process and then generate ads for. So it's likely not what Kyle think it is. The reality is, that Facebook already knows so much about him, that they don't really need to listen in on him.