1. slang An extreme, life-threatening physical reaction to some narcotic, especially heroin, opioids, cocaine, or amphetamines; an overdose. My friend died from an overjolt of laced cocaine. I don't touch the stuff ever since. I just stick to smoking weed—no risk of an overjolt on that stuff.

2. slang To experience an extreme, life-threatening physical reaction to some narcotic, especially heroin, opioids, cocaine, or amphetamines; to overdose. My brother actually overjolted on morphine after getting addicted to it following his surgery. I thought you were overjolting from the way you were sweating and your eyes were rolled back in your head.