Started a new contract:
Dev: "here, take this draft document containing a rough explanation of the requirements and write this service that exchange messages with these two subsystems"
Me 😐"ok"

-- couple weeks later --

Dev: "oh btw, you should go through ALL the fields in those messages described in the 'documentation' and double check them because we use millimeters and they use meters, we measure milliseconds and they use seconds. You should handle conversions when you deal with those messages"

Me (in my mind): "fucking son of a bitch! Why didn't you tell me this little piece of information at the beginning so I could have accounted for that instead of bloating the code now with your spaghetti style, full of horrible hacks, ifs and workarounds?
Me 😐: "sure, I will"

(don't worry, in the end I managed to find a clean solution for that 😉)