Does anyone know the origin of this phrase? I said it at work today, and no one had heard it before. I thought it was a pretty common thing to say.
A ne’er-do-well is a person who ne’er (never) does well, hence an irresponsible person.
The OED dates it to 1737, so maybe your coworkers are just really behind the times.
Where was it first used though?
Allan Ramsay, A Collection of Scottish Proverbs. (1737): Some ha’e a hantla fauts [a good many faults], ye are only a ne’er-do-well.