When you work on an issue and are really frustrated about it and turns out it was your own mistake that error appeared. Often best to find a second reason other than the real one.
Developers who thinks they know all libraries are worse than those who admit they don't know every library. I guess some people spend their whole life studying libraries, but that doesn't move them much in having a unique knowledge. And coffee, I only drink it about once a day but I do love it with sugar and milk :P