targuman sent:
noting, “I know the phrase ‘Idle hands make the Devil’s workshop’ (or similarly ‘Idle hands make for the Devil’s work’) but I don’t see the Devil working here…just hopping. I get that the idea is sort of like a kid leaving Legos on the floor, but it just doesn’t quite connect for me.”
We have a guess as to the intended story/joke here, but figured we’d let the assembled braintrust have at it.
Comics I Don't Understand 
The proverb has several variations. A couple have to do with idle hands being playground or playthings.
Yes, I think it goes “Idle hands are the Devil’s kids’ playthings” most often, right?
One variation is that idle hands are the devil’s playthings. I guess in this case, idle hands are the devils’ playthings. Devil Jr. 1 and Devil Jr. 2, to be exact.
I have always (I’m 76) heard it as “the Devil makes work for idle hands” and assumed the sentiment was behind most youth organizations such as 4H, Scouts, Little League, and so on: if you keep’em busy enough they won’t have time to get into trouble. The cartoon seems to turn the idea on its head. The stray idle hands are making work for the Devil, or more likely for his wife (or housekeeper?).
I was a little kid when I heard “Idle hands are the tools of the devil” and I pictured the devil down in his basement workshop with a whole lot of hands hanging on the pegboard.
As opposed to “An idle brain is the Devil’s playground” but that’s kind of tough to cartoon.
The “Devi’s playthings” version is well-known to me. He voiced passively.
“The “Devi’s playthings” version is well-known to me.”
Same. This was an LOL for me.
“Idle hands are the devil’s playthings” definitely.
Arguably the best known version of the phrase. Referenced in one of the best episodes of Futurama.
https://en.wikipedia.org/wiki/The_Devil%27s_Hands_Are_Idle_Playthings
And one has to “keep the young ones moral after school” – “The Music Man” uses the devils plaything in the song “Trouble” (“right here in River City”)
And when I saw “The Music Man” as a kid, I pictured a little-kid devil happily swinging on a swing in his idle-brain playground.
Mark in Boston – :-) !!