Question: has koko ever killed a kitten?
Answer: In December 1984, All Ball escaped from Koko's cage and was hit and killed by a car. Later, Patterson said that when she signed to Koko that All Ball had been killed, Koko signed "Bad, sad, bad" and "Frown, cry, frown, sad, trouble". ... To celebrate her birthday in July 2015, Koko was presented another litter of kittens.