Mop guy

Who coined the "mop guy" and what is the job of a "mop guy"?

No idea who started it, although the UK had a fictional character called Mrs Mop 60+years ago.

A "mop guy" is either (for our nautical chums) a rope that secures the mop (!) or, perhaps more likely, the man (guy) that uses a mop (material-ended cleaning stick) to clean floors. Mop guys works in supermarkets/shopping centres/malls and in public buildings like schools and hospitals. I suppose it is a lower job than being a janitor, as it only involves washing-down the floor.
Didn't "Good Will Hunting" feature a mop guy?