If you had the chance to place a curse on someone, would you?

If you were told by an old man that you had the ability to curse anyone, but it would last for 6 months, then fade away. Would you curse anyone, presuming you could curse as many people as you pleased? Would you curse a person that every time they ate something sweet it would taste like rotten fish or every vehicle they drove would suffer fatal mechanical trouble, etc? If there were some unknown side effect, negative to you, or someone you cared for, if you used it on the wrong person, which you had no way of knowing, would you be quick to use it, or employ caution?