In The Ringworld Engineers Larry Niven posits a pleasure Taser. Imagine you are a cop and you are faced with a man brandishing a weapon, maybe holding somebody hostage. The man is clearly in pain, angry, anguished. But also dangerous. And you have to neutralize that. So you point your Tasp at the man and remotely stimulate the pleasure center of his brain. The tension goes out of him. He relaxes, smiles. He laughs at the gun in his hand and lays it gently on the ground.
Or, in Niven’s more innocent scenario: “A dour stranger wanders past, rage or misery written in the sour lines of his face. From behind a tree you make his day. Plink! His face lights up. For a moment he’s got no worries at all.”