Wiktionary
dumb shit
a. (context idiomatic vulgar pejorative colloquial English) (alternative spelling of dumbshit English) n. (context idiomatic vulgar pejorative colloquial English) (alternative spelling of dumbshit English)
Wikipedia
Dumb Shit
"Dumb Shit" (also known by the censored version title "Dumb S**t"), is a song by American singer Tyrese. It features vocals from American rapper Snoop Dogg. It was released on March 10, 2015 as the first single off his sixth studio album Black Rose, on the record label Voltron Recordz.
Usage examples of "dumb shit".
I won't say it's easy or any dumb shit like that, but it's not all that hard.
You dumb shit, I thought, it's not Rimbo, it's Rambot, or Rambeau.
At this point Bud Schwartz considered ditching the dumb shit altogether and pulling the job alone.