Analogies involving socks:

• The Axiom of Choice is necessary to select a set from an infinite number of pairs of socks, but not from an infinite number of pairs of shoes.
  
  
• Quantum entanglement: when you have a pair of socks and you put one of them on your left foot, the other one becomes the "right sock" no matter where it is located in the universe.
  
  
• If g and h are elements of a group, then (gh)^-1 = h^-1 g^-1 .
  You take off socks and shoes in the opposite order that you put them on.

The first is from Bertrand Russell.
The second I came across on Tanya Khovanova's site (under Math Jokes; it's not a serious analogy for entanglement).
The third came from a web search for analogy with socks.

A father and two young sons were hiking in the rocks near were I was climbing today. One of the boys was exploring an area under some rocks which led to a discussion of possible hazards:

boy:	There could be giant snakes in here.
dad:	Maybe even a centipede. I hear they're dangerous.
boy:	Centipede. That was a video game from the 1900s.

I like roads that carry two opposite-direction routes. I am, of course, easily amused. US 36 west and Colorado 119 east coëxist on a stretch of 28th Street in Boulder, Colorado. I think there used to be west/east signs there but I could be wrong (my recollection is from about 35 years ago). Who knows why west/east designations are absent now. Maybe someone deemed the incongruity too confusing or jarring.

A typewriter I used in the 1970s had two keys with interchangeable type elements. The piece shown in the pic was part of a set of math symbols.

Time lapse video of my Joshua tree flowering: