I was placed at the company I work at 9 years ago and it was a college recruitment. Due to the recession in 2007,and its effects in 2008,although I graduated in 2008,my company called me only in 2009,roughly after an year of passing out. I really needed the job. After joining the firm,we were all inducted and had our official ID's and email accounts created. There was a mentor to me,who sat right across.
I was naive and had left for lunch without locking my system,only to come back and see the horror:

"Your resignation has been submitted" in bold ,as a wallpaper.
I was shocked and had lot of things in my head because earlier that week some firms had given "pink slips" and it was all over the news.
Finally,my mentor told me he did it for fun. Have never left my system unlocked ever since!