"By your age, he could turn a whistle into a watch and have it sing you the time."
Bartemius Crouch Jr, disguised as Alastor Moody, to Harry Potter[src]

This spell could be used to transform a whistle into a watch.

Cedric Diggory was capable of performing this spell by the 1991-1992 school year, according to Bartemius Crouch Jr, who was disguised as Alastor Moody at the time.

Behind the scenes

  • Given that Crouch Jr had only met Diggory that year, and he knew nothing of Diggory's talents prior, it is possible this is a hypothetical spell that does not truly exist.