To waste time.
To cheat; to swindle.
To molest.
To masturbate (especially of women).
To totter, like a child learning to walk; to daddle.
To manipulate a value at the level of individual bits (binary digits).
The penis.
In percussion, two consecutive notes played by the same hand (either RR or LL), similar to the drag, except that by convention diddles are played the same speed as the context in which they are placed.
A meaningless word used when singing a tune or indicating a rhythm.
To piss away: to waste or squander time, money, etc.
He piddled away three hours at the bus station waiting for Gabe to show up.