I think he liked doing that, there are so many examples of things that seem made up, but then you find they aren't. Making perfume from whale vomit, for example.
He often took real occupations and set them in his fantasy world to satirize them.
His humour was to take something from our world, put it in discworld, and then point out how ridiculous it all was.
What always amazed me was the diverseness of it. Whether he was taking the mickey out of hollywood, newspapers, rock music, somophore, stamp collecting, he seemed to have an eclectic knowledge about so much.
But not savagely, it was with the gentle fondness that underlies the best humour of friends ribbing each other.
His knowledge, wisdom and love of humanity was something special.
Granny Weatherwax lives around a mountain range called the Ramtops, after RAMTOP on the ZX Spectrum.
The Clacks optical telegraph network can contain routing instructions in its messages, and its operators basically have a hacker culture. They also have a group called "the smoking GNU," with GNU being a set of instructions for the message routing.
The wizards have a computer named Hex, which is powered by ants that move data around, so it has a label that says "Anthill Inside."
They’re not pixies, but pictsies. Their accent is a bit Scottish. They seem to have blue colored skin, but actually those are tattoos and they believe they’re currently in the afterlife (and must have been really nice persons in their previous actual life because they’re convinced they’re currently in heaven)
I always found that a bit lame and over the top.
The I learned that in northern england there once lived a keltic clan called the Picts. They were covered in blue tattoos and the kelts famously believed they lived in the afterlife and life was so good they were convinced they lived in heaven.
My favourite aspects of the pictsies ('Nac Mac Feegle') was their fear of writing, given its association with lawyers.