The Bouba/Kiki Effect is somewhat my area of expertise because I conducted my own research on it as part of my undergraduate dissertation. It is a relatively unknown gem in the mist of linguistics and sets out to find a link between the sounds of phonemes and the shapes of objects. There is overwhelming evidence in support of a sound symbolic relationship between certain shapes and certain sounds. In my study (2012), both English and Chinese students matched animal drawings with names in the expected way and this was most likely due to the Bouba/Kiki Effect. This effect allows most people to agree that when given a pointy, star-like shape and a round, blob-like shape, the first should be named 'kiki' while the latter should be named 'bouba'. Ramachandran suggests this is caused by a crossover in the brain which links the jaggedness of the sounds in the word 'kiki' with the jaggedness in the star-like shape of 'kiki'.
My study gave further support for Ramachandran's idea by using a large variety of animals that could be matched to a selection of names. For example, a long, snake-like creature was frequently matched to the name 'snarg', while a polka-dot jellyfish was frequently given the name 'blibib'. All of this evidence creates a very convincing argument that there is something built into our brains that links a variety of sounds with specific shapes. This could mean that not all things around us are labelled randomly and could add to the list of sounds that directly imitate our surroundings, such as onomatopoeic expressions.