I cannot wrap a present halfway decently if my life depended on it.
I cannot use chopsticks. I have tried, people always try to teach me when I am eating Chinese food. I can’t do it!
I can’t write while speaking. If I try, I end up writing what I’m saying.
I can’t maintain my composure while waiting at a light behind some chickenshit who can’t pull into the intersection and turn left without an explicit green arrow.
I can’t drive a manual transmission. Never have, never will.
I also can’t roll my Rs the latin way, with the tip of my tongue. The best I can do is the Germanic, back-of-the-throat roll.
I can’t flirt.
On the other hand, I’m pretty good at present-wrapping and chop-sticking. I can even juggle.
Walking.
Well, more precisely, walking more than 20 steps without doing myself an injury ranging from embarassing to “damn lucky that’s all you broke”.
I used to do origami as a child. Not seriously, not to the point where I’d design my own stuff, but I was able to follow directions pretty well and made everything from antelopes to dragons to zebras. Well, not zebras. Anyway, despite this, I can’t wrap anything. It doesn’t matter what shape it is. Simple cube? Nothing simple about it. An envelope? Nope, still looks like crap.
I can’t swim. Never learned. My dad always said he would teach me, but it never happened. We weren’t “water” people - no boats, rarely went to beaches, never went to aquatic centres, etc. Wasn’t required in gym class.
My husband is a “water” person, and he promises he’s going to teach me to swim. I hope so. I’m getting tired of being the only one at the beach with a life jacket on. 
I can’t whistle. I’ve tried all my life. Lots of people have tried to teach me, to no avail. I think my mouth must be broken.
I am completely unable to kiss a supervisor’s ass.
(Although, there was that one supervisor, if she had only asked…)
I can’t read! (dum, dum, DUM)
Oh, wait…
I can’t tie a balloon.
Oh, and I can’t drive a motorized vehicle.
My mom can’t snap her fingers. She makes the motion but no sound comes out. Very odd.
I can’t carry a tune. And I’m tone deaf - but I don’t know if that counts as a simple skill.
I can’t whistle or snap my fingers.
I can’t whistle anything more than a faint monotone “whiiiiiiiirrrrrr”. Those people who can put their fingers in their mouth and whistle down a taxi? The ones who can whistle a song, or like a bird? Yeah, I hate them all.
I can use chopsticks. I even use those great big ones for cooking.
I can wrap presents.
I can’t skateboard. I know it’s not really a skill, but I can roller skate and ice skate…just no ability to remain vertical on a skateboard.
I am also chopstick-impaired.
I can whistle pretty well (“Me & Julio Down by the Schoolyard” solo & everything!), but I can’t do that loud, fingers-in-the-mouth whistle you use to call the dogs/kids/clowns.
I tried to learn how to shift gears on a motorcycle, but failed.
There are two that I can think of.
- Folding T-shirts & polo shirts. My wife and daughter can hold up the shirt facing them, one hand on each shoulder, and then they do this thing and fold both sides to where they meet in the middle. Then fold the shirt in half longways and they’re done. I can not do the first motion. They’ve had their hands on my hands, and I still can not get it right. Seems so simple, huh?
- The one-handed cut. Cutting a deck of cards–you hold the deck in one hand, drop, somehow, about half of the deck into the palm,then with a quick motion, maneuver it up and over the bottom half. Looks impressive. The mechanics seem simple. But again, despite coaching from an expert, I can not get it right…
I know it sounds crazy, but there you are.
I haven’t been behind the wheel of a car since 1975, so it’s fair to say I can’t drive.
I can’t use chopsticks, either, but that’s OK because I don’t like Chinese food, so I never have occasion to use them.
I can’t whistle with my fingers, although I can carry a tune whistling the regular way. It bothers me that I can’t whistle really well. I know some people who can do it so well, it sounds like a musical instrument, with the vibrato and phrasing and all that. My wife can’t whistle at all.
I can’t dance to save my life.
I can’t whistle.
I can’t see those stupid magic eye pictures that were all the rage a couple years back. Ever see Mallrats? I could totally sympathize with the poor guy who was standing there the whole movie trying to figure out what the picture was supposed to be, while everyone else was walking up to him and seeing it instantly.
I am unable to recognize flirting when it’s aimed at me(either that or no one has ever tried to flirt with me). Similarity, I am unable to flirt.
I can whistle “canary bird style”, people have even been known to recognize the tune. I actually can carry a tune better when I whistle it than when I sing!
Can’t sing 
Can’t do the “shepherd’s whistle” thing, the loud ones.
Can keep up 5 or 6 conversations at the same time so long as they are all in writing, even if they’re in different languages (but it’s got to be my two best languages, Spanish and English); can’t do it if one conversation is actually spoken.
Can’t get most alpha-males to hear my voice. Not sure if it counts as their hearing problem or my speaking problem, though.
Can’t shuffle packs of cards including more than 40 cards (Uno, double-decks). Can’t do those “whoosing” shuffles, only grab each half of the pack loosely and insert one half into the other.
Can’t park backwards.
Can’t understand sports. At least the competition part of them. Specially the people whose pleasure doesn’t seem to come so much from winning as from watching the other guy lose.