Green’s Dictionary of Slang

1. (also pop-pop) a hole in one’s sock or stocking [? one’s flesh ‘pops out’].

1995

P. O’Keeffe Down Cobbled Streets, A Liberties Childhood 171: ‘You’ve a poppy in your stocking.’ The poppy would have grown bigger as we struggled home, the hand-knitted stitches loose and rambling.

2. a potato [the flesh ‘pops out’ when baked].

1996		(con. 1950s) C. Kenneally Maura’s Boy 42: Nan heaped the poppies, bursting out of their jackets, on his plate.
2001		G. Coughlan Everyday Eng. and Sl. 🌐 Poppies (n): potatoes.

3. (Aus.) a punch, usu. in pl. [pop n.¹ (3a); ? + link to the flower’s colour, i.e the red of the blood drawn].

1904

Sydney Sportsman (Surry Hills, NSW) 16 Mar. 6/5: Hock suddenly came again [...] and put some beauties out of his bunch of poppies about both jaws.