1. [techspeak] To move information from a fast-access memory to a slow-access memory (swap out), or vice versa (swap in). Often refers specifically to the use of disks as virtual memory. As pieces of data or program are needed, they are swapped into core for processing; when they are no longer needed they may be swapped out again.
2. The jargon use of these terms analogizes people's short-term memories with core. Cramming for an exam might be spoken of as swapping in. If you temporarily forget someone's name, but then remember it, your excuse is that it was swapped out. To keep something swapped in means to keep it fresh in your memory: “I reread the TECO manual every few months to keep it swapped in.” If someone interrupts you just as you got a good idea, you might say “Wait a moment while I swap this out”, implying that a piece of paper is your extra-somatic memory and that if you don't swap the idea out by writing it down it will get overwritten and lost as you talk. Compare page in, page out.