[pbhjpbhj]

Interesting, the other colours are all references to real things, I think. Blue mould; purple-faced (lilac) angry people; green of (say) a diseased limb, or as we describe someone's face when they're vomitous.

So, what is "hot pink": Hot metal before it's red hot? A blushed person's skin??

[sloppycee]

Maybe it's from 'haute pink'?