1. Try this game: Ask people these questions, in this order: "What's 1+1? What's 2+2? What's 4+4? What's 8+8?" Then ask them to name a vegetable. They almost always say carrot.
2. When arguing with someone, act much calmer than them. This can cause them to say something particularly irrational which you can use against them.
3. Nodding your head while asking a question makes the other person more likely to agree with you.
4. When high-fiving, look at their elbow and you'll never miss.
5. If you have a song stuck in your head that you can't seem to get out, think of the end of the song and it should go away. This is due to something called the Zeigarnik effect, which is basically your mind having a problem with things left unfinished.
6. If you want to get your child to do something, say, drink milk, do what Tigerlily1510 says: "Ask your son if he wants milk and he'll say no, but ask him if he wants milk in a blue cup or a red cup and he'll choose a colour and drink his milk! Magic!"
7. Use silence to your advantage when negotiating. People have a natural tendency to be uncomfortable with silence, and will often do whatever it takes to break it. Just be patient.
8. If you want someone to believe your lie, add an embarrassing detail about yourself. For example: "Instead of saying, "No I wasn't at Jimson James' house. I was with Randy the whole time." Try saying, "No I haven't been to Jimsons' in a while. I clogged his toilet so I don't think his parents want me over there for a while... so me and Randy hung out."
9. When you tell a joke in a big group of people, the person who you turn to look at first is the person you're closest to.
10. Do this to someone: Tell them to look into your eyes and say they can't stop looking.
Ask them what they had for lunch three days ago and chances are they won't be able to answer. It's very hard to remember something without moving your eyes.
11. Whispering something to someone almost guarantees that they'll whisper back.
12. When trying to find something, look right to left instead of left to right. You're more likely to miss things because your eyes are used to looking one way.
13. If you want someone to believe a totally untrue story, repeat it three separate times adding details each time. For example: "You can say to someone 'remember that time at school, when Mr Smith accidentally ran over the math teacher in the teacher's car park?' The first time they won't and will question you, but then repeat the same thing later with a couple of details thrown in and the third time you mention it, they will remember it happening."
14. According to SpenFen, use the power of priming. For example, Tell someone this: "What is the word spelled 'S-H-O-P'?" Make sure that they say: "Shop." Then immediately ask them: "What do you do when you come to a green light?" Their answer will likely be wrong."
15. Having someone do a favor for you is a good way to get them to like you more.
16. If you're playing a game against someone and you want them to mess up, ask them how exactly they're playing so well. They'll overthink it.
17. If you want to mess with someone who's counting something, say a set of numbers in order instead of saying random numbers. They're brain will catch onto the pattern.
18. From Two_Times_Thirty: "Bet a friend/family member that they can't taste the difference between whole/2%/1%/skim milk, or some combination thereof. Blindfold them and have them begin tasting the milks. Now, replace the last milk with orange juice. The brain prepares the body for milk, and the unexpected acidity usually causes a gag reflex, and sometimes vomiting. Keep a bucket handy."
19. Let's say you're carrying something you don't want to be carrying. Easy fix, just follow rarabara's advice: "If you want to get get rid of an object, for example walking with a friend after you bought a 2l coke bottle and want him to carry it, just keep talking to him while handing him the bottle, most of the times people will just take the object automatically without thinking."
20. Here's how to win rock, paper, scissors every time: "Right before you are about to count (or interrupt the count) catch the person off-guard with a personal question, or something directed at them. Then immediately after just resume the count like nothing happened. Most of the time the person will throw scissors as a sort of automatic defensive mechanism."
21. Use your eyes to control people, according to unimatrix_0: "People naturally look in the direction they want to go, so they'll look at your eyes to ascertain which way you're heading. This also means you can divert someone else's path by looking in a direction that would cause a collision."
22. Finally, the master of them all, according to farceur318: "Go up to someone in a restaurant and tell them to close their eyes and picture a playing card. While they are doing this, eat as much of their food as you can and run away."