My nemesis at my previous job was a major bullshitter and everyone knew it, except some management. Woe be to those who actually listened to him - it never ended well for them. Other managers knew better, or at least were warned.

Nice guy, but a complete moron professionally.

I recall one time he was telling a group of us about a test he and management wanted to do. "No changes to the software," he said, repeatedly. Looking around the room, I knew no one believed him (well, he believed it, I'm sure, but no one else), but we all knew it was pointless to point out that he would be proven wrong. And he was, of course. (He wasn't a liar, just an idiot.)

This dude would do everything he could to make me look bad, sometimes in front of external groups, other times in front of management. I never complained, but others complained to his supervisor on my behalf, and he'd apologize, then do it again a few months later. Again, it wasn't malice, he's just an idiot and doesn't think.

One time I got him. He asked if we had planned for a workload that was higher than some people expected, and I was able to say, "Actually we budgeted for even more than this." A woman that worked for me, when she saw I was having a bad day, would ask, "Hey remember when you showed up Bob in that meeting in front of management?" It always improved my mood. Some coworkers are gold.

One time, he was set to become my supervisor, and I was like, yeah, I'm gone if that happens. Fortunately, it didn't.