goose egg

From the oval shape of both a goose's egg and the Arabic numeral zero (0).

goose egg (plural goose eggs)

1. (Canada, US, informal) Zero; nothing.

   Synonym: duck egg

   I missed every question on the quiz and got a goose egg.

   • 1949 March, I. A. Horowitz, “Readers' Games”, in Chess Review:

     Grandmaster and grand duffer alike prefer the all-important point to the ignominious goose egg.

2. (informal) A swelling caused by a bump on the head.