Perspire profusely; also, suffer mental anguish. For example, We were sweating bullets, sitting in the sun through all those graduation speeches, or It was their first baby, and David was sweating bullets while Karen was in labor. The bullets in this expression allude to drops of perspiration the size of bullets. [Slang; mid-1900s]
tv. to suffer about something; to be anxious or nervous about something; to sweat blood. The kid sat in the waiting room, sweating bullets while the surgeons worked on his brother.