From the Dr. Seuss Book Oh Say Can You Say?. This is a greedy ape who doesn't eat only bananas but he mostly has a craving for cakes made with grapes, and as he gobbles them, he stops and tells the viewers "The greener green grapes are, the keener keen apes are to gobble green grape cakes. They're GREAT!"
In the "Oh Say Can You Say?" video, segment to the "Hop on Pop & Other Stories", the ape uses the catchphrase of Tony the Tiger from the "Frosted Flakes" commercials, "THEY'RE GREAT!"