There is some nuance. Coworkers at my level are always fair game. A boss? Depends on the boss. Well adjusted bosses I have a great working relationship with? Definitely. Those have been the majority of my managers over my 20 year career. Bosses with an unhealthy demeanor or an axe to grind? Or executive leadership? No, unfortunately not. In those situations, I've found success in conversations with their peers or someone from HR lets a pay band slip. People like to talk, people like attention. YMMV.

When someone asks me, to show I'm honest, I provide my paystub. I accept that the data I receive might not be accurate, but that doesn't stop me from trying.