This story kind of reminds me of a time I almost lost my job..
I work at a Best Buy, and I use to keep a backpack with me when I would go to work to store clothing/personal items in. I would always put it in the employee breakroom (where..you know..only EMPLOYEES can get into) and go about my day. Well the store had issued a policy that ALL employees that were not Supervisors or Managers could no longer carry cell phones with them on the sales floor. Since I worked in the wireless cell-phone/mp3 department at the time, i was allowed to carry my iPhone as a demo for customers who were interested in the Ipod Touch.
My girlfriend at the time however, would always put her iphone (that i purchased for her) in my bag. Well on day when I got off from work I go to check my bag and get her phone when sure enough, it was GONE!! FIVE HUNDRED AND THIRTY FOUR DAMN DOLLARS OF MY HARD-EARNED CASH STOLEN OUT OF THE EMPLOYEE BREAKROOM!!!! Not only that, but they got me for my 30gb Zune ($267.49 at the time) AND my PSP ($188.99 at the time)
Needless to say I totally FLIPPED!! I was EXTREMELY angry not just that my things had been stolen ut by an EMPLOYEE (Note, I'd been working at that particular store for over 2 years and was on extremely good terms with everyone who worked there and had never had any personal probems with anyone)
Worse yet, it happened over our Tax free weekend, which for anyone working retail in the state of Georgia can attest, is a very busy and tiresome four days. I had just come off of working a double shift and all of mythings are gone. ..

This is the ONLY time in recent memory that I can remember just totally blacking out and cursing out every single person who was in earshot. My GM was trying to calm me down and i yelled in his face and told him I quit and I took off my Best Buy shirt and threw it on the floor in front of customers and everyone. I was completely done, I couldn't understand how ANYONE whom i WORKED with could laugh, joke, and be a co-worker with me and then STEAL from me

The ONLY reason i wasn't done and fired then and there was because my direct Supervisor and Manager pleaded with the GM on my behalf after i stormed out of the store. Once I calmed down and apologized to the GM face to face he was very understanding of how hurt I was.
And to this day the lesson that i learned was, never trust your co-workers no matter HOW long you've worked with them..