I call dibs on the last slice of pizza! I get dibs on top bunk! When Steve moves on to his new job, I call first dibs on his cubicle! When someone calls or gets dibs on something, they are claiming a right to it before anyone else. But where does this playful expression come from?
Dibs may have originated from a children’s game called dibs, played much like jacks but using sheep knucklebones or pebbles, themselves known dibstones, shortened to dibs. (The pronged shape of modern jacks may even imitate the knobs of the bones.) The Oxford English Dictionary attest this dibs in the early 19th-century, though the game itself is ancient.
As for the dib in dibstones? It may come from a verb dib, “to tap lightly,” related to dab. The “first claim” sense of dibs emerges by the 1920-30s. The term may have been pushed along by another use of dibs, 19th-century slang for “money,” a corruption of division or divide.