If you truly hate someone give them a baby bear. Comment from Historical source. Nobody mentioned Bears just get big. But what if you give them a pregnant female house cat? -- Anon Guest
Across societies, across worlds, there are things that could be counted as gifts - but definitely aren't. Drum kits for the hated one's children. A bear cub. A baby ape. A dragon's egg. All of those and more can only be called trouble. And then there is the coup de grace of malevolent gifts for a despised individual.
A pregnant housecat. Specifically, a fluffy pregnant housecat. Which makes it difficult to tell that said cat is even pregnant at all.
Sadistic observers know well what happens next. The cat will have her litter in a secret place, safe and secure for her kittens. The new owner will not be immediately aware that they are even there. Cats, of course, are stealthy predators that can also be prey. It's in their vested interest to conceal their helpless young. Then the owner suddenly finds out that they have four to six cute, fluffy little kittens of doubtful parentage. But they are adorable.