Sure there is such a thing as a "pencil barrel." We're having a conversation about one right now. Everyone here seems to know what it means. Even you.
It's called a
col·lo·qui·al·ism
/kəˈlōkwēəˌlizəm/
noun
1.
a word or phrase that is not formal or literary, typically one used in ordinary or familiar conversation:
Now, excuse me while I duck for cover.![]()
You're absolutely right. Some people are way to anal and just want to find a way to argue. As you said, every single person here knows exactly what you mean. If we didn't develop new words and phrases for things, we'd all still be speaking Ye Olde English. Same people that throw a fit when you call "stocks" grips. It gets annoying.