the rough edge of your tongue
the rough edge of (one's) tongue
A harsh scolding or rebuke; a verbal lashing. The teacher gave us the rough edge of her tongue after she caught us reading comics in the back of class. I know you feel they deserve the rough edge of your tongue at times, but you need to show some restraint or you're going to lose their respect.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
the rough edge (or side) of your tonguea scolding.
Farlex Partner Idioms Dictionary © Farlex 2017