Very heavily, unsubtly. This expression originated in early nineteenth-century America as “a thousand of brick,” presumably because bricks in such quantity were more commonly counted than weighed. “If folks is sassy, we walk right into ’em like a thousand o’ brick,” wrote Caroline Kirkland (Forest Life, 1842). Sometime in the early twentieth century it was replaced by ton, which has survived. Thus, to come down on like a ton of bricks means to reprimand or punish severely. This colloquialism dates from the first half of the 1900s. The novelist Graham Greene used it in Brighton Rock (1938): “If there’s any fighting I shall come down like a ton of bricks on both of you.”