[fr a bridge term for winning all the tricks in one hand]
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with grand slammer
A sweeping success or total victory, as in This presentation gave us a grand slam—every buyer placed an order. This term originated in the early 1800s in the card game of whist (forerunner of contract bridge), where it refers to the taking of all thirteen tricks. It later was extended to bridge and various sports, where it has different meanings: in baseball, a home run hit with runners on all the bases, resulting in four runs for the team; in tennis, winning all four national championships in a single calendar year; in golf, winning all four major championships. In the 1990s the term was used for four related proposals presented on a ballot at once.