Usually if you catch a stranger looking at you. When you look back at them, often they will pretend to be checking what time it is. They will check their wrist watch as if they have to be somewhere or as if they are running late. I’ve seen this tons of times if I am looking down as I walk down the street and as I raise my head I see someone that was previously looking at me, they try to disguise immediately by checking their watch. Thus if you look at the someone and they immediately check their watch, chances are they were staring at you.
Here is another way to know if someone was checking you out. Have you ever been riding the subway and yawn and then suddenly you catch someone yawning as well. It probably means they were staring at you. In fact you could try this, by forcing a yawn and then look around and see who else is yawning and boom, that person, was probably staring at you.
Have you ever heard the saying, keep your friends close but your enemies closer? Well there is psychology behind that statement. Let’s say you are going into a meeting at work or at school and there is someone there that you know hates you or dislikes you. You may even fear that this person will attack your presentation or your statements. Well, just sit right next to that person. You may feel uneasy at first, but find comfort on the fact that your enemy will feel uncomfortable as well by your proximity and the chances of criticism or attack will be much less, than if you are far away from that person.