English Teacher Melanie: Expression Explained – “A Lean, Mean Polluting Machine!”
In the listening lesson ‘The Licence Plate,’ I was angry that I had to pay for an emissions test for my car even though my car had passed the same test two years ago! I said …I doubt my car had become a lean, mean polluting machine since the last test, but I had to spend $35 for the test anyway.
A lean, mean ___________ machine is a popular expression in North America! If someone or something is a lean, mean _________ machine, it is exceptionally good at its purpose. It is impressive, efficient, and excellent at what it does. The noun used in the expression is usually a gerund, but it can be anything.
My car passed the emissions test 2 years ago. I keep my car in good condition, so I doubt that in two years, my car had suddenly turned into a car that was emitting gases and other substances at dangerously and harmfully high levels.~
This phrase is believed to have originated in the US Army, where they trained soldiers to be lean, mean fighting machines.
It was later used in the American movie Stripes:
“You’re a lean, mean, fighting machine!”
(Bill Murray as John Winger – Stripes)
Champion boxer George Foreman later introduced an electric grill called the lean, mean fat-reducing grilling machine.

He went from being a lean, mean fighting machine to selling lean, mean grilling machines.
Other uses of the expression:
A lean, mean research machine.
McAfee AVERT Stinger: A Lean, Mean Virus-Killing Machine.
Lesson #3: Make Your Company a Lean, Mean, Operating Machine.
Let’s look at this expression in more detail!
The general definition of mean is, of course, ‘not nice or good.’ In informal American English, it has another meaning = very good, excellent, impressive.
She makes a mean chicken casserole!
(Her chicken casserole is excellent, delicious.)
He plays a mean guitar!
(He plays the guitar very well.)
The same goes for the word machine. If someone or an organization is a machine, it means they are very efficient, very good and very quick at what they do – just like a machine!
Roger Federer [a tennis player] is a machine!
Our company operates like a well-oiled machine.~
Do you know anyone or anything thing that is a lean, mean ___________ machine?~