Yes, twice, actually!

Both were very early in my working life - early 20s - and I believe both were the direct result of superiors feeling they could take advantage of a young person.
1st was a retail job. I'd worked for them for over a year before going away to school, then coming back a year later. They immediately re-hired me, and asked if I'd be the interim manager because they'd just had to clean house and trusted me to get things going in the right direction again. It was definitely inferred that I'd likely remain manager. Within days, I noticed that we regularly weren't balancing at the end of the day - 30 cents over one day, a dollar under two days later, etc. I reported this to the main office over and over, asking for security to come help me find out what was happening, but they said they weren't worried about it, being so little.
All of a sudden, though, I was transferred to another store, where I wasn't given access to the cash registers. No explanation was given. After a week, I asked my new manager directly what was up... and kind heart that he was, he told me he'd been told to "watch" me because they thought *I* was the one stealing. I went straight to the computer, emailed exactly what had gone down to every employee in the company and quit then and there.
About 6 months later, the new manager at my old store called me, introduced herself and let me know that it was discovered that all the top supervisors of the company were found to have been involved in the losses and had been let go. She hoped I'd consider coming back as all my old employees raved about me and she needed an asst. manager. Um, no.

But it was nice of her to offer.
YAGE #2 was in the restaurant biz. A spilled drink at the service bar caused me to slip and fall flat on my back, causing me to lose consciousness and seriously screw up my back. The company couldn't have been better; workers' comp took care of everything and the company's risk mgmt. office echoed my doctor's orders that when I was cleared to go back to work, I still wasn't to carry trays with more than 2 plates at a time for a while. No problem there - I was scheduled for sections that didn't contain tables with more than 4 seats and had the full support of our GM and staff... except for the new asst. manager "Bob" who was just a jerk. One night, he announced that he gave me a table of 20. I said that was fine, so long as someone would help me with drink and food delivery, since I couldn't carry that much at once. Bob announced that the other server on duty (this was 12am, and we closed in an hour so we were down to 2 servers) was too busy and he, Bob, wasn't about to help me. I could take the table he gave me or leave. So I did. Leave.
The next morning, the GM called, apologized profusely, and begged me to come back. I told him I'd love to - if I'd never have to work with Bob, which, of course, was impossible. To his credit, the GM remained a wonderful reference for many years after that and I never once regretted leaving.
