Diddle

"Pride is a sin." "Priests diddle kids."

Paul was the first one to unzip his pants, take out his diddle, and make himself ready to pee on the wire.

[…] a long, wooden porch good for listening to coyotes and owls, with a glass of diddle at hand.

'No one ever got rich being honest,' the father said. 'Customers are there to be diddled.'

And, when his forward strength began to bloom, / To see him diddle up and down the Room!

What's that tune that goes "diddle di-dum, diddle di-dum, diddle di-dum-dum"?