1. Extremely prolonged eye contact
I know it has been done before, it's a cliché, but if you really want to freak someone out this is a great starting point.
2. Asking someone if they have been crying, when they clearly haven't been.
This will make anyone question whether or not they are hiding their sadness... from themselves.
3. Laugh really hard in a genuine manner when you are alone in silence with a person (keep laughing until it gets extremely weird).
This would definitely freak me out, I highly suggest.
4. When you meet someone for the first time tell them you had a dream about them.
Straight up terrifying, try and give a weird amount of detail when explaining the dream.
5. Correct someone on your name, making up a new name each time you meet them (causing them to think they are going crazy not knowing what your name is).
This is a good one if you don't want to be friends with someone but they can't take the hint.
6. Drop something in front of a stranger and stare at them until they pick it up.
Great to do in a quiet, yet crowded place, like an airplane or a play.
7. Take a picture of someone you don't know that well, make it your phone background then show it to them.
Preferably a close up of their face. Also, this is super creepy so make sure you pick someone who at least kind of knows you.
8. After someone says something say "that's what I just said", even though you didn't, and look at them confused.
You really have to stick to your argument with this one. Also, try to do it when someone says something really specific to make it extra weird.
9. Randomly start breathing really loud and fast and tell everyone you don't know what they're talking about when they ask if you're okay.
This will definitely freak people out... maybe too much.
10. If someone lightly touches you scream and jump back.
This will make for some serious awkward silence, always remember to say "I'm just messing with you" after this one.