I can’t draw simple geometric shapes well. E.g., a straight line or a circle. Carries over into my penmanship.
Depth perception? I have trouble with that myself. Ask me how far away I think something is and I’ll have no clue.
Left/right gave me trouble until I started wearing a watch in junior high. The watch was on the left arm. Eventually I didn’t have to think about it. I haven’t worn a watch in 20 years.
My drawing skills are pathetic. I was forced to take a drafting class in electronics school and struggled to pass. It always came out messy and smeared from too much erasing.
Other responses have reminded me that when someone spells something out loud to me before I know what the word or name is, I get completely lost halfway through. So getting email addresses over the phone is a bit nightmarish sometimes, because for some reason it takes about a whole second for my brain to recognize someone saying the letter “m”, that I need to write that down now, and then getting my fingers to actually write that letter (and not some other letter). By that point they’re already on to letter two or three.
If they tell me what they’re going to spell out ahead of time, even if I don’t fully get what they’re saying I can anticipate the letter they’re probably going to tell me and do okay.
I have no trouble writing or spelling in any other situation and I can even spell plenty of words out loud without writing anything down - it’s just a funny disconnect that I have.
Another one. I can’t often read my own handwriting and even my own hand printing is sometimes questionable. While I attribute it to carpal tunnel, it has been steadily going downhill since I was a kid.
Huh. Doing some more reading on this. This author says it is a word confusion. Which seems to go with my experience. It’s not that I don’t know the difference for right and left, but I have trouble accessing the correct word. If I say “right” I may in fact mean “left.”
I suck at giving directions and usually tell people that they really don’t want to ask me.
I am dyscalculic (it’s a real thing) – directions, visualizing physical things being described, the most simple grade-school math, I can’t do any of those things without great effort. Like other sufferers I have a lot of work-arounds, from turning back to look at my path to memorize landmarks so I won’t get disoriented (including places nobody else bothers to do this), counting on my fingers under the table, etc. I cannot remember any number whatsoever unless I write it down – if I measure length and width of an object, for example, I will not be able to remember the length in my head.
It has caused difficulties in a number of avocations – I can’t learn music theory, for example, although I have excellent pitch-matching skills and musical memory and tone.
When there is a radio and a television going at the same time (or two different stations of either, or either and a kid’s electric noise toy), I can’t filter out one or both. My mind goes into a feedback loop and I have to leave the area. Conversations (even one-sided cell phone conversations) are sometimes hard to tune out, but it’s possible for me to do so.
Since nobody else seems remotely bothered by this, ever, I have to assume it’s some sort of defect in my brain. I don’t even know what to call it or why that would be the case. It’s really common for mid–level restaurants and bars to have both TV and radio.
I can’t snap my fingers with my right hand. Left? No problem, daddi-o. The right, I’m like a disabled crab.
I can’t pass a field sobriety test even when I’m sober. I have it worked out in my head what I’m going to say if I ever get pulled over by the cops.
There’s a pose in yoga called “easy-sitting pose”, but it’s really difficult for me to do. When we do it, I just smile and go over to the wall. The wall is my friend.
I cannot snap my fingers.
I have never been able to do it. People have tried to teach me; I just don’t get it.
I’m another one who can’t recognize faces well. I’m sure that’s one reason I’m so socially unsuccessful.
I can whistle but what I can’t do is the really loud - fingers-in-mouth style whistling. If I try I just make raspy blowing noises and dribble down my chin.
Left/right confusion here as well. Like some others, if I’m walking around I’m fine but if I have to verbally give someone directions I often have to stop & think (“watch on left wrist”).
I can’t read in a car, to the point I can barely glance down at a map even if I’m the passenger. Almost instant motion-sickness. I can’t use in-ear headphones or any kind of ear-plug to reduce noise for the same reason. 
I can’t either, not really. I did it once, but haven’t been able to do it since.
I have a question for those that say they can’t swim - are you able to float? Just curious.
This is fascinating by the way.
Oh lord am I happy to see all you other people in the 5-year-old left-right confusion club. I’ve felt so lonely there my whole life!
What else…
I have never been able to stretch to touch my toes, or to do a side-split, but I CAN do that thing where you kneel down, and then settle onto your butt and lean back all the way til your whole back is on the floor. Apparently (according to martial arts instructors, yoga teachers, and my phys-ed professor) this combination is quite odd.
I can’t roll my rrrrs, or make any of those interesting germanic cat-hurling noises correctly.
I am quite bad with knowing where I am in space. I constantly bump into things, and I have the bruise collection to prove it. Apparently most people grow out of this after they finish their growth spurt - I never did.
I have never ever ever successfully braided my own hair. I think this is related to the left-right thing and the “where I am in space” thing, but it never works. I’ve tried by feel, I’ve tried in a mirror, I’ve tried with my eyes closed… nothing.
I also find it incredibly painful to throw up, and it takes forever. I’ve only thrown up 10 times in my entire life (at most), so maybe it’s a lack of practice.
I have trouble multiplying my 7s.
My husband’s entry in this list would be that he cannot, no way no how, float. We went to Manitou Lake (an inland salt-water lake) where everyone is supposed to be able to float - he couldn’t float there, either.
Interestingly enough, his dad had his hips replaced in the last couple of years, and his surgeon was impressed by how very dense and strong his bones are. I suspect that my husband’s bones are the same - very dense, to the point where he can’t float.
That reminds me of another thing I don’t really do - bruise. I can bruise, but it takes a whole lot of damage for a bruise to actually show up. It really cuts down on the sympathy I get for boo-boos. 
I never understood how the L thing was supposed to help, for this reason. It’s interesting that some people don’t know ‘left’ from ‘right’ (or have trouble) but do know which way the L faces.
I write 3s backwards often. 4, 5 z and n sometimes as well. I used to have trouble with b and d but I don’t any more.