Come Out Of The Woodwork Meaning

(idiomatic) to appear or emerge unexpectedly or inexplicably, frequently in large numbers or quantity.

Example:   He won the lottery last year and he has had old "friends" and distant relatives coming out of the woodwork ever since.
1992, Robert P. Newman, Owen Lattimore and the “Loss” of China, page 227:
  Would-be informants came crawling out of the woodwork, drawn to McCarthy as moths to light, each peddling a new version of Lattimore's evil deeds.
2006, John Marsden, Circle of Flight, The Ellie Chronicles: 3, unnumbered page:
  And suddenly they came out of the woodwork. I don't actually know what that expression means. What come out of the woodwork? Cockroaches maybe. Mice?
2012, Enzo Centofanti, Out of Africa and into America: The Odyssey of Italians in East Africa, page 136:
  With the fall of the fascist regime, Italy was virtually overrun by several political parties who came out of the woodwork to fill in the vacuum.