Met someone with this on Halloween. She sees colours on the letter and numbers she reads, and it has developed so that she tastes them slightly. Some numbers like 2 and 4 will combine to form the colour of 8. She also lucid dreams every night though can't control it sometimes, she's just aware that she's dreaming. So she's always conscious. Her mind sounds so interesting...
She also does a lot of drugs because I think they are especially crazy for her.