One interesting thing you notice when you watch enough cartoons and read enough comics from the olden days is that plagiarism isn't as modern an invention as you might think. Even in the thirties, when it was still possible to think up a new gag that hadn't been done before, you'd still see examples galore of stealing a joke from a rival and hoping to get away with it.
Even so, it surprised and entertained me to find the original (or maybe just an earlier iteration) of an Oor Wullie strip in an earlier Popeye comic:
Thimble Theatre starring Popeye, December 18, 1932
Oor Wullie, January 30, 1938
Five years and the Atlantic Ocean between them - I wonder if there's a missing link here? I don't think Thimble Theatre had made it to British newspapers yet at that point, huge though it was in the USA, and I don't think that gag was ever used in the animated Popeye cartoons...
See, this is the kind of thing that really fascinates me, so I thought I'd share it with the world in general.