(And no, I don't mean clockwork ones.)
The new baby grandson of a friend of mine loves waving his arms and beating the tray of his high-chair with great energy and considrable rhythmic, double-handed skill. The unmarried elder brother of the infant's father enjoys winding up his brother and sister-in-law and plans to buy the child a drum kit.
"His arms are strong but he isn't walking yet so he probbaly wouldn't be able to manage a bass drum and hi-hat. However a snare drum, various ton-toms and a range of crash cymbals should keep him entertained for hours. Perhaps a set of bongos might be better?"
Sounds a good plan to me. Do any readers know of any better children's Christmas presents for winding their parents up - or of any better wind-up presents generally?