I have a coworker who insists on talking to me like I have 0 knowledge in my field despite me actually having more experience and a higher job title than him. He also lectures people like he is their manager even if they have been there longer than him. I even listened to him "reprimand" his own supervisor!
He just gave me a lecture the other day on how to install a network printer... I've been in IT for 8 years now and in a hell of a lot more industries than he has.
I told him that he needed to bugger off and let me do my job. He got royally pissed at me and I told him that he's not even in my department and that he has zero authority to so much as advise the people in IT. If he wanted to give us input, he could change departments and be fully trained, but that he would be at the bottom of the ladder with everyone above him. If he didn't like that, then he needed to go do his own job and let the rest of us work in peace.
He's not even really good at his own job. Most everyone here hates him; everyone that he deals with on a daily basis says he messes stuff up constantly, and even though he's not the head of his department, he still talks to his manager like he is.
Some days he will change his email signature just by adding random shit that he is assigned to do and the add "coordinator" to the end. So one day he is a "training coordinator" even though that's not an actual title and no one gave it to him. Sometimes we like to reply to his emails and change his title on the email he sent to us to random shit, luckily he hasn't noticed that yet.
He also makes the schedule for his department. All departments rotate shifts every week between morning, nights, and weekends. It just so happens that it the two years he's worked here, he has never been scheduled to work a single holiday weekend. Weird how that works. There was even a time where someone left that department for another, and then 2 weeks after she moved, he scheduled her to work a holiday weekend.
Let that sink in. If we follow the rotation like every other department, it would have been his weekend to work. However he is so selfish that when he couldn't rope his other co workers into working it, he had to schedule someone that works in a completely separate department... He's even done this to his own manager but she's just so nice that she won't say no.
Pretty fucked up thing to do to your coworkers, just dumping them with more work because of your own laziness and apathy.
Also this dude will sit at work with his hand shoved elbow deep in his pants. And not its not like a "I'm adjusting" kinda thing because I get that, but I walked up to ask him a question and midway through his response he just shoves his hand in his pants and continues on as if nothing is off..... like really bro?