Someone once said "To mill, is to be milled". What he meant no one knows, but when you're milling, you're in your room not doing anything in particular or worth your time.. but you're happy with that. It's a student thing.
Dude, I can't be arsed. I'll be in my room, milling.
In the times of Pugilism under the London Prizefight Ring Rules, British gents used this term as a verb to mean fight, thrash, beat, and box.
Bill Richmond proceeded to mill his opponent Dockey with such severity, Dockey was left completely blind.
The milling of those two pugilist was quite the sight to see.
an alias for an ugly person, someone with a fetish for backpacks or hats.
Person 1: he is such a milling!
Person 2: Yeah I know he is so gross