It is a term used in Spain to refer to a man effeminate slang and derogatory way. It is synonymous with gay, homosexual, pirobo, crazy. In Spain, Sarasa is also a surname used in Pamplona, Navarra province.
Eunuch, by extension, gay, homosexual, effeminate. It comes to the Spanish from Arabic, but you probably have a Hebrew history where there was a similar word for "castrated" or "celibate".