- something appropriate only for children.
- something very easy or simple.
Origin of kid stuff
An Americanism dating back to 1925–30
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Idioms and Phrases with kid stuff
Something very easy or uncomplicated, as in That new computer program is kid stuff. This usage alludes to something suitable for young children, or “kids.” [c. 1920]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.