This video shows a young Koko (age 2) running and playing on a grassy area at the San Francisco Zoo. While Koko is exploring, she frequently checks in with Penny. During these moments of joint attention, Penny models the sign for “Flower”. The gorillas used the same sign for “Flower” and “Stink”.

Later, Koko (age 28) uses the sign while looking at some paper covered in flowers. This sign was used frequently by Koko, she even used it to title one of her paintings – “Pink Pink Stink Nice Drink” — based on a photo she saw in a book of pink flowers along a river bank.

And Koko's younger male companion Michael used this sign to name a beautiful painting he did of a bouquet of flowers. He called it "Stink Gorilla More."