Something or someone insignificant: that idea is just small beer
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 small beer
small potatoes. Of little importance, as in Don't listen to Henry; he's small beer, or It's silly to worry about that bill; it's small potatoes. The first term alludes to a beer of low alcoholic content (also called light beer today) and was used metaphorically by Shakespeare in several plays. The variant may have been invented by frontiersman Davy Crockett; it was first recorded in 1836. Also see small fry, def. 2.