Interestingly I very nearly did. On my ICND2 exam I thought I'd mistyped the password to a box on a simulation.
At the very beginning of the simulation question.
Turns out I had entered it correctly but was mistyping it on subsequent attempts, saving me from hosing a huge chunk of marks due to a finger fumble.
For some reason I couldn't get 'Danger Zone' by Kenny Loggins out of my head for the rest of that entire exam.

I thought I didn't read the entire simulation description correctly and all the way to the end thought I'd forgot to configure each device and not just drag and drop the correct interfaces and ip address. I was so mad at myself, thought for sure I had failed the exam.. I was more relieved to see that I received a 100% on that section then the actual passing score. Funny how that works hu..