Lisa's Date with Density a child from Josh Weinstein's school days who everyday would get onto the bus with a piece of toast, which had Vaseline on it. A majority of the story is a reference to the film "Rebel Without a Cause". Lisa remarks that Nelson is "like a riddle wrapped in an enigma wrapped in a vest", a reference to "a riddle wrapped in a mystery inside an enigma"; this was Winston Churchill's opinion of Russia at the outbreak of the World War II. In its original broadcast, "Lisa's Date with Density" finished 63rd in ratings for the week of December 9–15,
The Riddle of the Sphinx (Inside No. 9) mini-tutorial for cryptic crosswords. Shearsmith, meanwhile, had never attempted a cryptic crossword before working on the episode, but has subsequently started completing them. Nonetheless, Pemberton acknowledged that not everyone enjoys crosswords, hence "I always hated cryptic crosswords. Why can't people just say what they mean instead of trying to trick you all the time?" from Shearsmith's Tyler. In an interview with Connor, published after "The Riddle of the Sphinx" had aired, Pemberton explored the ways in which writing for "Inside No. 9" was like writing for a cryptic crossword; in both cases, misdirection is key and utterly arbitrary choices or