The misusage of conyo/coño is very interesting. So coño in spanish really means bastard/cunt and we pinoys use it as a derogatory adjective to refer to a person that is someone that is Spanish. The Filipinos hated the Spanish before as you know because of all their cruelty. So every time a pinoy sees one, it's automatic "conyo" because they were bastards to us.
Nowadays it
has evolved to someone that is mayabang/speaks english. Why? Well first of all
we have to look at its usage before: We used conyo to refer to someone that is
Spanish because the Spaniards were cruel, mayabang and different from our
society. It sort of retained it's meaning because to most Filipinos, especially
the masses, if you speak english, you're mayabang and different from the
society.