As a word, diddle isn't quite as old as fiddle, although as a sound it was (and is) prominent in Gaelic lilting. ... Like fiddle, diddle can also mean cheat or swindle, and this definition likely originated from Jeremy Diddler, the conman in James Kenney's 1803 play Raising the Wind.

Where did the term fiddle around come from?

Wordman Charles Earle Funk has the funky idea that the phrase came about because the shape, form, and musical tone of violins were so pleasing that they invited complimentary comparisons to human beings.

What does diddling mean?

transitive verb. 1 chiefly dialectal : to move with short rapid motions. 2 : to waste (time) in trifling. 3 : hoax, swindle.