I’m quite fond of optical illusions, where your brain is tricked into seeing something that isn’t there or can’t exist. You also get physical illusions, where your body creates sensations of things that don’t or can’t happen. I want to share three illusions, although only one would strictly fit those criteria. For all but one you will need a partner, otherwise there are no special requirements.
Paralysed Hand
For this illusion you will require a partner.
You must start by squeezing your partner’s hand, or a similar sized object, for about 60 seconds. You should squeeze hard but not so hard that you hurt your partner. Once the time is up, you must relax your hand but do not open it! Just stop tensing the muscles. Your partner should now slide his or her hand free and lightly tickle the inside and outside of your hand for a further 60 seconds. Once that is done, you should slowly try to open their hand.
You should find it very difficult, and possibly a little painful, to straighten your fingers. As a child, I would usually try for a few seconds and then use my good hand to straighten them.
Puppet arms
This one can be done alone, although you will need a door frame or walls that are a similar width apart.
Stand in the middle of the door frame with your arms at your sides. Keeping your arms straight, bring them up as if doing a star jump until your wrists meet the sides of the door frame. Try to lift your arms through the door frame as hard as you can and continue doing so for about 40 seconds. After that, you can put your arms down and step out of the door frame.
If you now just relax, preferably with your eyes closed, your arms will start to rise of their own accord.
Through the floor
For this one you’ll have to recruit a partner again.
Lie face-down on the floor with your arms stretch out in front of you. Your partner will now need to lift the front half of your body (Your hips should remain on the ground) by your wrists and hold you up for approximately 40 seconds. During this time, you should let your head hang down and keep your eyes closed until the end. Once the time has elapsed, your partner should gradually lower you flat again, being especially careful when your head meets the floor.
As your arms are lowered, it should feel as if they descend past your head and through the floor.
I’ve personally tested all three of these and got them to work with variable success rates. If it doesn’t work the first time then try once or twice more, perhaps increasing the time slightly. I hope you have fun with these. They should be particularly fun for children, but I’m sure people of all ages can enjoy the strange sensations.
Evidence & Reason 
I took part in the most bizarre trick when I was still at school, and it seems in a similar vein.
One classmate sits on the floor hugging his knees, arms akimbo, back straight, head level. Four other students press down hard straight on his head for about 30 seconds (possibly compressing a vertebra or two, but you know how kids are).
Then something really weird happens…
If the four students clasp their hands together with only their index fingers extended, they can easily lift the sitting student from the floor by hooking the extended fingers under the shoulders and knees of the sitting student (i.e., one student per limb).
I did this myself (I was on left knee detail) and I still can’t explain it. All I know is, (i) the effect only lasts about 2-3 seconds, so you’ve got to do the lift quickly; and (ii) without the pressing down on the head first, it’s completely impossible – you can’t even come close to lifting your mate off the floor.
Any thoughts on this apparent anti-gravity trick?
It’s because your body was pushed hard and the weight is low because it’s used to the pressure making it lighter than before,after a few seconds from you pushing down your body thinks it’s light and then remembers it’s heavy…..
Doing physica theray post knee replacement I had the experience after doing hamstring stretches of feeling like my R foot was sinking into the floor when I started to walk. It has happened 3 times. Very odd sensation.