The owl in nature is a bird that eats its prey, and vomits out what it can't digest. So then it seemingly wouldn't need to poop, but yet it still does. Calling someone else an "Owl" in context is a nicer way of explaining that the person is unnecessarily rude, aggressive, arrogant; or in other words an unnecessary asshole. It's the kind of person who is hateful not because it's been a bad day, they got barked at in the office, they stepped in cat feces, nothing is wrong. They are just rude for no apparent reason or offense. Some people are owls periodically, whilst a rare type is usually an owl, and this is the kind of person most people always avoid. The owl may be generally unfriendly, or inflict sporadic outbursts upon others.
Mike: Hey I heard you got transferred to another department, what happened?
Sarah: It's just my supervisor James, he's really good at troubleshooting but he's such an owl sometimes that I had to leave.
Mike: makes sense, after awhile the stress can't be worth it.