throw caution to the winds
Also, throw discretion to the winds. Behave or speak very rashly, as in Throwing caution to the winds, he ran after the truck, or I'm afraid she's thrown discretion to the winds and told everyone about the divorce. This expression uses to the winds in the sense of “utterly vanishing” or “out of existence,” a usage dating from the mid-1600s. The first recorded use of throw to the winds was in 1885.