Jamieson, Fausset and Brown on Exodus 32:2

2. Aaron said, ... Break off ... earrings--It was not an Egyptian custom for young men to wear earrings, and the circumstance, therefore, seems to point out "the mixed rabble," who were chiefly foreign slaves, as the ringleaders in this insurrection. In giving direction to break their earrings, Aaron probably calculated on gaining time; or, perhaps, on their covetousness and love of finery proving stronger than their idolatrous propensity. If such were his expectations, they were doomed to signal disappointment. Better to have calmly and earnestly remonstrated with them, or to have preferred duty to expediency, leaving the issue in the hands of Providence.