double whammy

Meanings

1. A series of two events that causes adverse effects; a twofold blow or setback.
2. A series of two events that causes positive effects; a twofold boon.

Etymology

From double + whammy (“evil spell; curse or hex”), popularized by the American cartoonist Al Capp (1909–1979), in his classic comic strip Li’l Abner (1934–1977).