Offer to share an apple with someone, then split it in half with your hands. It’s easy once you figure out the technique.
Dollar bill origami. Ask someone for a bill, fold it into a T-shirt or whatever, and give it back to them.
Wear a ring (stainless steel, not gold) and use it to open bottles with your hands.
Obligatory Bob Mortimer https://youtu.be/F21mTojMCAc
If you can solve a Rubik’s cube, normal people will think you are a genius. On the other hand, actual cubers correctly assess that I am a dumbass if they see me do it.
I know exactly one party trick based on mathematical group theory, which I have actually used to impress non-mathematicians at a party.
There’s a concept called the “center” of a “group”, which is the set of operations that commute with every other operation in the group. The center always contains the identity operation of doing nothing. The group of scramblings of a Rubik’s cube happens to contain exactly two elements in its center: the identity, and a move called the “superflip” which takes a little bit of effort to memorize how to do, but it’s not so hard. Much easier than actually solving a scrambled Rubik’s cube. It’s like you do a simple move repeated 4x, and then you do that whole 4x set 3x with some rotations in between. Not terribly complicated. Importantly, once you memorize it it’s not difficult to do just by feel, since it’s a fixed sequence of mechanical motions.
So, the party trick goes like this:
You have a Rubik’s cube that is exactly a superflip away from the solved state. You hand it to an unsuspecting party guest and say “go ahead and make one or two turns” (it’s important to say something like “one or two” because if they do 3 the trick becomes challenging, and if they do 4 or more it might become impossibly difficult unless you’re actually good at solving Rubik’s cubes, which I am not). They take this obviously unsolved cube and make a couple more moves so now it appears even more scrambled.
You take the cube back and do the superflip behind your back, without looking at the cube.
Then you move the cube out from behind your back, and at the same time (trying to be slick about it) you undo the one or two moves remaining before it is solved. Everyone gasps and say “omg he solved it behind his back” (when really you did no such thing).
This works because if S is the superflip and X is the simple moves they did to it, S X S is equal to just X because S commutes with everything. (S is also its own inverse, so that S S = 1.)
Okay here’s my favorite super easy card “magic” trick. Works best prefaced by “I’m not very good at it but I hope it works”
You fan a deck and tell somebody to remember the card. Then ask them to put it back on top of the deck. Make sure to remember the card on top of the deck first. Then you give the cards a very shitty shuffle, but enough so they can see their card go into the middle of the deck. If you look really awkward and unskilled, this will work even better. The card they picked and the original top card should remain together.
You then just start flipping cards off the top of the deck, 1 by 1. at some point you will flip the card that was on top of the deck, meaning the card just before it is the card in question. Keep flipping a few cards. Then (make sure you look hesitant and unconfident), say “Okay if the next card I put on the table is your card, you down your drink. If it’s not, I’ll down my drink” If your performance has looked shitty enough so far, they will be sure to agree, since they already saw their card be flipped.
But instead of flipping the next card, you go through the pile, find their card, and put it back down on the table.
I’ve done this one before and it’s always worked for me. The one difference I do is after they put the card on top of the deck I give them the deck and tell them they can cut it as many times as they’d like. By cutting the deck it’s incredibly unlikely they’d separate their chosen card and the top card. Plus it makes them think they have more control over things
That’s risky depending on how adamant they are about cutting. If they’re cutting a random spot each time, at 10 cuts there’s an ~18% chance they’ve split the two cards up. Your odds are 50/50 at 35 cuts.
