People make it weird by acting weird. Nobody was looking at you when you entered the room but if you be fidgety and nervous then viola! You've made people look at you and made it awkward. Seriously. I've had this experience so many times. Even when you've done something wrong, just apologize and say that "I'll do better" and watch the reaction of the other person. While if you act all guilty and just stare at the ground, of course it's going to piss someone off and this was something i realised really late. So, the next time you have any thoughts like:
what if it looks bad?
what if they think I'm weird?
what if they talk bad about me?
what if they talk behind me?
In most cases, you're the one in this situation and your brain is indirectly controlling you into doing things that actually prove your thoughts so in other words, you're messed up by your own mind.