One of the best I've ever heard: "The Graveyard Couple"
Mr. and Mrs. Thompkins, who've been very happy together for 12 years, currently, are experiencing a phase of boredom and stagnation. To change things up, Mr. Thompkins gets an idea: Have sex in a near-by graveyard.
With a mix of reluctance and excitement, Mrs. Thompkins agrees and they go off...
What do you call a country without females?
A civilization of sentient deer may sound interesting
But I get the strange feeling that they'd make no progress in advancing their own culture once they come into contact with humans.
I guess that's what happens when you encounter Stagnation
What do you call a country run by a bunch of stubborn old deer?