Top 10 Things Most Humans Can't Do With Their Body
Let's take a look and see if you could actually do these things. Don't get worked up if you couldn't, though. They are proven to be almost impossible to do.
It's about impossible for most people to lick their elbows; only one person in a hundred can lick their elbow according to unofficial estimates. Unless you've been blessed with a short upper arm and an abnormally long tongue, there's no way you could be able to do it, no matter how hard you try.
I hate my elbow, it talks to me a lot. My conscience and my elbow keep fighting all day.
Whenever I hear this, all I think of is that one scene from iCarly where Spencer is trying to lick butter off his elbows

A part of the brain, called the cerebellum, monitors our movements and can distinguish whether sensations are expected or unexpected. Since it is trained to predict sensations when an action is caused by your own movements (but not if someone else's), if we attempt to tickle ourselves, our brain prepares itself for it. In short, the brain prevents us from self-tickling.
However, there are actually some people who could do such thing. Because of their inability to distinguish self-initiated actions due to neurological changes in the brain, people with schizophrenia are able to tickle themselves. So while they are aware of their own intentions and movements, their brain's ability of notifying the person's body about it is impaired, and therefore their brain cannot prepare itself for the tickling.
You can't tickle yourself, because tickle is when you can't tolerate the touch, but since it's you touching you, you expect it.

Most people can't keep their eyes open when they sneeze, with the exception of a few people. According to experts, it is the "sneeze center" of our brain that sends an involuntary reflex to clamp our eyes shut during a sneeze; it happens automatically. One age-old myth claims this is to prevent your eyes from popping out, however, it is actually the body's way of preventing germs from entering the eye.
It seems technically impossible, but I don't believe either that it would make your eyes popping out. Most people seem to fall for the myth.
I did this and now I'm frantically searching for my eyeballs which popped out.

Even when I was 9 I was able to do this I am not a contortionist but at that time I was dancing for four years at that time it is painful though I could do this without warm up.
It can be done with lots of patience & consistency in physical flexibility.
I once did that. Takes a bit of stretching.
Takes a lot of flexibility, but I saw a video title where someone claims to do it (Never watched it though).
That takes flexibility skills. Contortionists can do that though.
I always try but never succeed. Maybe if I become more supple...

Most people can actually raise their eyebrow, but it's usually just one of the two eyebrows. The ability to raise both one at a time is quite rare, but with practice, you'll be able to train your muscles to do it.
I can only do this involuntarily, when someone says or does something stupid, suspicious or aggravating. The same goes with rolling my eyes.
I can raise my right eyebrow easily, the muscles around my left eyebrow don't seem to allow it though.

Rolling your tongue is rather common; at about 25 percent of people are able to do it. However, not many can fold it backwards or make shapes like a spaceship or clover leaf. These all require muscle control and tongue dexterity, though some claim this ability indicates to the dominant genes.
I con (sort of) do the bottom left one, but I don't understand how someone could do the bottom right!
I can only do the bottom right one, not the other three.

Most people can't touch their nose and chin with the tip of their tongue; just about 10 percent of the population can. In medicine, the ability to do this act is called the Gorlin sign.
I once couldn't do it, but now I can. (Nose)
I can touch my chin, but not my nose.

Most people can't put their entire fist in their mouth, since a human's hand is usually a lot bigger than the opening of their mouths. A few are able to do this, however, simply because they have small fists and big mouths.
Having to get it out would be painful.
I can actually do this one.

Most couldn't wiggle their ears; only 15% of people can. But, fear not, for you could still train yourself to do it!
I can do that. I use to wiggle my ears to annoy my hairdresser when I was a kid.
How does it even work?

Most people can't twitch their nose, unless they have a "Hemifacial Spasm". In fact, even Elizabeth Montgomery, the actress who portrayed Samantha Stephens in Bewitched, just moved her lip to make it seem like her nose was twitching, when it really wasn't.
What's that? Watching twitch all day and sticking your nose to the screen?
I have to move my mouth like most people.

I can do this on my left hand but not on the right
Edit. I can't really do this on my left hand either if we're talking about the 2nd joint but the 1st is still much more flexible than that if others or my right hand
I looked it up on the internet and now I am 100% sure my thumbs are double jointed at the 2nd thumb joint.
I can do that but at the lower joint than the one in the picture.
This is really easy for me!
I also can do this

I can do this! It's fun to freak people out with it.
This is very easy to me
I can almost do that
That can be done easily by going on thrill rides, watching horror movies in theaters, going to haunted houses, meeting stars you've anticipated so much, doing extreme athletic moves, or not following your healthy routines of each day.
I saw a T.V. programme as a smaller child where people (professional magicians) could do very extreme things with their body. The only one I remember was a rather chunky man who could make his heartbeat stop for almost a whole minute.
Why would anyone do that
Hard but I can do it
I would do this when I was like 9 years old.
I can't do that
Actually, no one can be completely steady as the body's designed to move & our motor skills are imperfect. Yet, we exert energy at the same time & experience fatigue. We're always unsteady & shaky & even when we sleep we move around.
Especially your belly?
I can be steady
I can see the back of me