The original line has Tobi dismissively saying, "Don't bother, Kakashi. That jutsu won't work on me."

Because of the way Japanese grammar works, a slight alteration of the sentence endings turns it into a desperate "Don't do it, Kakashi! That jutsu will work on me!" This version made its rounds on the Japanese internet, turning it into a rabid meme that still persists today. These days it's usually used as a response towards images of saccharine cuteness or mouthwatering food. i.e. "No more pics, please! My heart/stomach can't take it!"