a) 1980's soft-rock band, much hated.
b) In Greek mythology, the river Styx was gaurded by Charon, and marked the way to either elysium, Tartarus or some grey fields with the pool of Lethe (From which the word lethargy is derived)
When you cross the river Styx, you shall hear music by Styx, and then you know that you're in hell.
In the days of racial segregation in Africa, people of mixed races, or those who looked like they were of mixed race were subjected to the penicl test to decide what race they were. A pencil was placed in thier hair, and should it fall through they were classified as white, and were given the priveliges that were assocciated with white people. Should the pencil not fall through thier hair, they were classified as black and treated as such.
The pencil test was humiliating, and even if someone were to be classified as white, they would still not be totally accepted, and would instead be refered to as 'coloured'.