I do a lot of programming for work and fun, and two annoying things I come across on a regular basis are the following: 
  1. "You should be able to do (X) even though I've never tried it."  Yes, you should, but you can't.  If you don't know what you're talking about and don't understand the language you're trying to use, don't just spout off answers from the top of your head like some sort of code gunslinger.
  2. "This code should work even though I didn't test it."  You're right, it should work, but it doesn't.  If you took two minutes to actually try it yourself instead of just typing it into the comment box on a website and assuming it would work perfectly, maybe you could've actually contributed something.  Instead, I'm left trying to solve my preexisting problem while also trying to solve the problems your code created.
Programmers are so full of themselves.  Buncha nerds. #technology