A difficult task will be halted near completion by one tiny, previously insignificant detail (adapted from Murphy's Laws)

A few weeks back I was having lunch with some post-docs and the rest of the recently "purchased" PhD crew. The conversation was already going on when I joined them, but it was easy to pick up from where I got. They were talking about the dumbest, most horrific, terrible humorous mistakes previous students (undergrads and graduates) had done. Obviously, they had a lot of consideration for the fact that most of these mistakes were performed by people who were still learning, and to be fair with their dignity, some of these mistakes happen because technicians, professors, supervisors, bench supervisors and other colleagues are way to concerned about their belly buttons and cannot spare 2 minutes with a simple induction that will spare everyone future fuss. 

So apparently, one student was asked to autoclave some tips in a box. And because he never went through that induction he thought that that specific black or blueish oblique marks on the autoclave tape were handmade. So he grabbed a pen and he did his best by drawing them on the surface of the tape, stripe by stripe the tape was filled with oblique lines. Job done, he went to his supervisor and told him with a very satisfied expression, the same expression held by one when you did a great job so suspiciously fast, "It's done. It's autoclaved".

Well, I wasn't there to testify, but I can imagine the loud laughter. But in my opinion everyone is entitled to do mistakes, what you cannot do or should try never to, is to do something like a robot, just because you were told to. Judge what you're doing, try to understand the nature of what you are doing and most of all question it if there is something you don't understand. Whatever time it takes, if you get it then you'll never have to ask again... or hear their out loud laughter. And listen girl, it was a few years ago and people still remember, so...