The Ten Fools are invoked for all manner of foolish action. Ten is a number of mythological and symmetrical import on Roshar. The Ten Fools are, essentially, the opposites of the Ten Heralds, each of whom represents an ideal.
"They’ll see me dead, like my father. Sometimes I do wonder if we’re chasing after the ten fools here. The assassin in white - he was Shin."
–King Elhokar, agreeing with Dalinar, doubting their current strategy in the Shattered Plains.
"They’re worthless, you know," Sadeas said. "You’re of the ten fools, Dalinar Kholin! Don’t you see how mad you are? This will be remembered as the most ridiculous decision ever made by an Alethi highprince!"
–Sadeas, commenting following the deal trading the bridgmen for the Shardblade.