I had a friend from high school that was a compulsive liar. we were friends for probably ~10 years and I never said anything because his lies were never hurtful lies. They were usually to entertain and were so obvious that any halfway intelligent person could spot them from a mile away. Fast forward to our early 20s and we're working security together. When I drive him home after a shift one day he started telling a story about how some guys tried to rob him with a knife outside his apartment but he turned the tables and took their knife and broke the guys arm in the process before they ran off. I finally asked him "what really happened?" and he looked at me hurt and didn't say anything. I later felt like a dick but his lies were growing in grandiosity to the point of offending some other people we worked with. A few months later he takes a shift with our supervisor who also happened to be a classmate and my buddy very intentionally fell asleep at the desk in the security office while using a second chair as a leg rest as the supervisor was doing a walking patrol of the building. Anyways, our supervisor came back and saw our buddy so the supervisor opened an emergency exit setting off the security alarm to see if he'd get up and respond. He did not. -That was my buddie's last shift. The following evening he texted me with some false explanation for why he was terminated. My response was "Dude, you were recorded on 3 different surveillance cameras sleeping next to the table we all watch the cameras on."

I didn't know that was the last time we'd talk. Less than 6 months later he had a bachelor party and a wedding neither of which I was invited to.