Things that I think normal 18 year old dudes should be able to do, but, for one reason or another, I cannot:
 
Ride a bike. I know its sad, right? I really have no idea why i can't do it other than no one ever taught me and I guess I never felt the need to learn. I think maybe I struggle with balancing my weight, maybe, because I can't ride a skateboard, either.
 
Hit a slow-pitched softball. After one game in a softball league, I am 0 for 1 with one strikeout. I struck out in a slow-pitch softball game. Yes, really.
 
Write in cursive. I probably haven't written in cursive since 3rd grade, then when you take the ACT, they make you write out some anti-cheating pledge in cursive, and the thing is about a paragraph long. It took me about ten minutes, and then i ended up just writing the print letters with line connecting them.
 
I'm sure there's more but thats all I can think of right now, so I ask: What normal things can you not do or are not very good at?