The common cormorant (or shag)
Lays eggs inside a paper bag,
You follow the idea, no doubt?
It's to keep the lightning out.
But what these unobservant birds
Have never thought of, is that herds
Of wandering bears might come with buns
And steal the bags to catch the crumbs.
(Christopher Isherwood)
I've always loved this ditty. I was reminded of it by a comment about people eating out of paper bags on another thread. Catching crumbs, I expect, and preventing greasy fingers perhaps.
But I thought I'd better be flippant somewhere else. Here is a good place.