I try to spend as little time as possible being annoyed over stuff, but one thing that can make me childishly angry is when I buy something new, unwrap it, and there is something wrong with it. Not wrong as in me having bought the wrong thing, but as in having got a faulty item. I end up being just as disappointed as a child getting a new toy that is broken. The fact that I can just hand the stuff in at the store and get a replacement for it doesn't help. It just makes me stupidly pissed. The feeling wears off quickly, though, but I get really, really annoyed. I only get this feeling with brand new items, and only when the problem clearly is not my own fault.
When I was about 13 years old my parent bought me a cheap stereo for Christmas. I was really happ, because I didn't have my own at the time, only a small cassette recorder. When I tried it out after unwrapping it, the cassette deck would only play at about half speed. Not a happy Christmas eve. Of course, we traded it in and got a new one when the stores were open again a couple of days later, but man, was I disappointed!
My oldest kid has the same issue. A few years back we bought a Skylanders game for him for our Wii console for Christmas. The box contained some figurines and a CD with the actual game on it. In the store all the CDs were taken out to prevent people from stealing it, and it turned out the guy who wrapped it up for us when we bought it had forgotten to put the disc back in the cover when we bought it. This was THE thing on my kids wish list that year, and he was NOT thrilled when we found out that the disc was missing...
I get the same feeling when stuff like this happens today. A complete waste of energy, but I just can't help it.