In geek culture, what is the number 42, and what is its peg?

42 → rain.

In Douglas Adams's The Hitchhiker's Guide to the Galaxy, 42 is the answer that a giant supercomputer called Deep Thought delivers — after 7.5 million years of calculation — to "the Ultimate Question of Life, the Universe, and Everything", the joke being that nobody actually knows what the question is. Adams later said he simply picked an ordinary, unremarkable small number for the gag, but it became a beloved in-joke woven through programming culture ever since. Peg 42 → rain: picture 42 drops of rain.