Why did the little pigs get fed up
with their father?
Because he was a boar (bore)!
What does a hedgehog have for lunch?
Prickled Onions.
What did the big chimney say to the
little chimney?
You're too young to smoke.
Why don't people play cards in the
jungle?
Because of all the cheeetahs!
What's a frog's favourite drink?
Croak-a-cola.
(Courtesy of a primary school in Sheffield and the Domesday Project of blessed memory:
http://www.bbc.co.uk/history/domesday/dblock/GB-436000-384000/page/6)
And in answer to your question - jokes, often in what some people see as poor taste, are one of the ways in which we make sense of tragedy and disaster. I suspect that there was a list of Somme jokes going around army messes by about the beginning of September 2016. Just like there will already be Aleppo jokes going around Syrian ex-pat groups around the world, and they will be laughed at by people who've lost close relatives.