Jam Tomorrow

Jam tomorrow or (older spelling) jam to-morrow is an expression for a never-fulfilled promise. It originates from Lewis Carroll's 1871 book Through the Looking Glass and What Alice Found There. In the book The White Queen offers Alice "jam every other day" as an inducement to work for her:

"I'm sure I'll take you with pleasure!" the Queen said. "Two pence a week, and jam every other day."
Alice couldn't help laughing, as she said, "I don't want you to hire ME – and I don't care for jam."
"It's very good jam," said the Queen.
"Well, I don't want any TO-DAY, at any rate."
"You couldn't have it if you DID want it," the Queen said. "The rule is, jam to-morrow and jam yesterday – but never jam to-day."
"It MUST come sometimes to 'jam to-day'," Alice objected.
"No, it can't," said the Queen. "It's jam every OTHER day: to-day isn't any OTHER day, you know."
"I don't understand you," said Alice. "It's dreadfully confusing!"

The Queen's rule is a pun on a mnemonic for remembering the distinction between the Latin words "nunc" and "iam" (sometimes written "jam"). Both mean "now", but "nunc" is only used in the present tense, while "iam" is used in the past and future tenses, much like one use of the English word 'then'. (It is not clear if Carroll invented this mnemonic or was merely quoting it.)