At my current firm, I found out that my co-worker, a new hire (22-year about a year out of college) was making $3k more than me, who is 10 years older than him. Spoke with my boss about this and they gave me a 30% bump. The HR reasoning was that they thought I was 'happy' with my current salary and that I had loyalty to the company because I've been with them for 5 years. A former coworker went to get an offer from another firm and tried to use that as leverage for a salary increase and ended up getting fired.