Me either and I’m 31! My excuse is that I got a horse around the same time I got a bicycle and riding a horse was far more exciting than riding a boring old bike.
I can’t snap the fingers on my right hand. I also can’t whistle, and can’t make the Mork sign with my right hand. I find this hand thing odd, since I’m right handed.
I can’t ice skate.
I can’t open plastic bags. Really. They defeat me every time - Crusoe reckons they’re my nemesis.
I also can’t say words with “ths” sounds in them.
I have never knowingly heard any part of Led Zeppelin’s “Stairway to Heaven” as played by the band itself - although I am aware of what it sounds like having had the misfortune to have heard the version by Rolf Harris.
Betcha five bucks you’re wrong.
I can’t post to TMI threads.
I can’t swim or ice skate. Well, I’ve never tried the latter, so maybe I can.
I’m SO glad I’m not the only adult on the planet who can’t swim 
I also cannot tolerate the glaucoma test, but I am double-jointed (left side only) which is very cool for freaking out grown-ups and impressing little kids.
Holy )*& - you can SEE SOUNDS? what do they look like?
I have trouble remembering how to lace up a new pair of shoes. After a couple tries I “get it” again, but I don’t do this often enough to have committed it to long-term memory.
It took me awhile to learn how to whistle, so I can do that, but only through my lips. I can’t do the type of whistling where one sticks two fingers in his mouth. I also can’t do the type of whistling that involves cupping the hands together.
I cannot cross my eyes. No matter how hard I try, I just cannot do it!
I can’t swim. My mom emrolled me in swimming lessons several times, but I could never get past the doggie paddle. Nowadays I never go to the pool or the waterpark. Nobody would want to see me in swimming trunks, anyway. Trust me on this one.
Oh, and I can’t get a date, either. 
I’m nearly 35, if that makes CynicalGabe feel any better (is that why you chose the name “Cynical”?)
I can’t sleep, most of the time.
I can’t eat chicken-- that stuff is vile, I don’t know how you people do it. On the other hand, I find turkey, duck, goose, rabbit, and frog all have very distinctive tastes that are only remotely similar.
I can’t whistle.
It impresses Trek geeks that find it appropiate considering your user name too.
I can’t turn my feet outwards. I was very pigeon-toed as a kid and had to wear braces to correct it. When I walk my feet point straight ahead, when I’m lying on my back my feet face inwards so my toes are facing each other. My feet just aren’t oriented the same as most everyone else’s.
I can’t bend at the waist and touch my toes. I’ve never been able to. I was a dancer for 13 years, and I couldn’t touch my toes then, either. I think my hamstrings are just too tight. Or maybe my arms are really short.
I don’t watch TV. I turned on the Illinois/Wake Forest game a week ago (GO ILLINI!), but that’s the first time I’ve sat down to watch anything since about May.
My boyfriend is 24 and doesn’t drive, but that’s mainly because insurance is too high.
That’s one of the few tests I don’t really mind. But there’s another one which I absolutely can’t take. It involves goopy yellow eyedrops that numb and relax your eyes. Can’t do it. I get nauseous and light-headed. Yes, from eyedrops. I haven’t figured it out either.
Me either, and I’ve actually had my optomotrist explain that I am physically incapable of seeing them and never will be able to.
I can’t make raspberry noises. You know, the “thhbbpht.” That one. Can’t do it. My mom makes fun of me.
I broke my kneecap ice skating, so “can’t ice skate” isn’t strong enough. I am a danger to myself and others!
Ooooh, I can’t see them, either. When they were all the rage a few years ago, it was quite frustrating. I kept looking at them, thinking, “WTF is it? What am I supposed to see?!?”
Never did figure it out.
Oooh, I can’t either. When they were all the rage a few years ago, I kept looking at them, thinking, “WTF is it? What am I supposed to be seeing?!?”
Never did get it. They just look like a fuzzy design to me.
I can’t snap, whistle, sit cross-legged, get a date, or sing in tune.