Prejudice is funny.
Not laugh-out-loud, early-Jackie-Chan-era-movie funny.
Funny, like, "Why like that wan, ah?" funny.
I think we tend to try too hard to organise people into categories we can understand. Just so that the realisation of each person's uniqueness doesn't overwhelm us. So that we can find some point at which we can identify with that person, because though we may not want to admit it, someone who's not like me may not be someone I want to know.
Or maybe we deliberately make the categories even narrower to suit our biases and prejudices. "I don't strike up conversations with people who clean toilets for a living." "I don't have friends who wear embarrassingly misspelt counterfeit designer clothes." "I don't want to be acquainted with anyone who wears sandals over socks." And gradually, the categories narrow even more and it gets harder and harder to find someone who meets our standards.
And one day, we wake up and realise we don't make the cut anymore.