In Puerto Rico, refers to people for the high and high-middle classes. Roughly equivalent to "preppy" but with a more douchebag feel, and more tropical, although sometimes makes for ridiculous copies, for example, wearing cold weather clothes in the summer in Puerto Rico.
They all live in gated communities, go to private schools, and shop in chain stores and shopping malls.
The children tend to have a fetish with lower class culture, but the older ones are conservative and hypocritical.
It is not a term of endearment, but one of derision.
It has its origin in the port-manteau of "guaynabito" and "bicho" (which in Puerto Rico means "dick").
"Guaynabicha" is the female equivalent.
"Look at that guaynabicho, he has an Abercrombie and Fitch sweatshirt on but its 100 dregrees out!"
"Only a guaynabicho would get mad that they have kiddie pools in the housing proyects - after all he has a swimming pool in his home and his beach house."