Tom the Dancing Bug, a/k/a Ruben Bolling, has a lovely bit of doggerel about the complications that arise from the gradual drift of copyrighted material into the public domain:
A bear, however hard he tries,
Grows tubby without exercise.
Edward Bear had barely started
When his body bent and farted.
You may not recognise his name,
but it’s the one in Public Domain.
He’s “Edward” here til ’22,
When Winnie’s copyright goes “pooh.”
(Explainer, in case it’s not obvious: A. A. Milne’s When We Were Very Young, which refers to a stuffed toy as ‘Edward Bear’, entered the public domain on 1 January; Winnie-the-Pooh, which identifies the same ursine companion as ‘Winnie the Pooh’, will not enter the public domain for another several years. Bolling evidently thinks that date will be 2022, though seventy years from 1956 (Milne’s death) would be 2026, as best I can reckon. Clarifications welcome.)