Mine was before my career started in earnest as I took a job during one of the summer breaks in college, worked 10-11h a day with a commute of 3h in total on top of that without even having a contract on paper only for my employer to first suggest I work for minimum wage and then not pay me at all after the first month.

Naturally, I walked, but to this day I can't believe how naive/stupid I was back then.