verb (used with object) Informal.
to mash or push, especially to push down or in; compress: to smush a pie in someone's face.
Origin of smush
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
1825 (n.), variant of mush. As a verb, by 1980.
Online Etymology Dictionary, © 2010 Douglas Harper