Meaning: having nothing to do leads to mischief
Rewrite 1: feet with nowhere to go lead to a footpath of trouble
Rewrite 2: twiddling fingers often go hand-in-hand with mischief
Rewrite 3: much evil is due when there’s little else to do (or when there's little to do, much evil is due.)
Rewrite 4: stay busy to stay sane
Comment: I found this one more interesting to rewrite than many others. It almost has a Confucian quality to it. Keep tongue in cheek when it’s wisdom you seek!
Note: I'm linking to www.wordsmyth.net for definitions, which is a service users will very soon need to register for. I don't think there's a cost involved. It offers a very nice set of features beyond what you may find on other online dictionaries. Some of these words are fairly elementary but I wanted to serve a wide audience, which would include children learning some of these words for the first time.