In the YA Whispering Woods series, Mia Taylor has synesthesia. This is a very real medical condition. Wikipedia explains that synesthesia is "a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway." How many people have are born with synesthesia? Wikipedia also says, "It is estimated that synesthesia could possible be as prevalent as 1 in 23 persons across its range of variants." In The Waiting Booth, Mia has multiple sensory overlap. She sees colors associated with sounds, voices, and people. In a kissing scene, she associates the experience with the taste of chocolate.
I've found lots of very scientific and analytical information about synesthesia, but some of the most interesting anecdotes come from YouTube. I found this video today and was very interested in the associations of this person. I laughed at the thought that Christian Slater is "cheesecake" and Hugh Jackman is "chocolate pudding." Watch the video to see the taste your favorite star is associated with for this synesthete.