A guy I used to know back in 2005, was about to hand in his final dissertation in Oxford University. His whole work, which took almost a year to do, was on the computer which was shared by his trusted friend.
The night before the hand-in deadline, his friends' girlfriend completely fucked the computer and the whole dissertation was lost. The guy noticed it the next morning and pleaded the professors to show mercy as this essentially fucks his whole grade. As you would expect that didn't happen and so 3 years in Oxford which would guarantee him jobs for the rest of his life, were gone. He graduated with the lowest mark and was forced to do a Masters (out of his own pocket) to cover it up.
Talk about fuck-up huh.