What is the origin of the Hebrew slang word chupar צ'ופר meaning "bonus" or "perk"? Ruvik Rosenthal in his Hebrew slang dictionary offers two suggestions.
The first is that it derives from the Spanish word chupar, meaning "to suck", either via Ladino or perhaps directly from Spanish. He suggest that if this is the case, it might be found in a phrase like "para chuparse los dedos", which is Spanish for "finger-licking good" (and in fact was used as the slogan for KFC). Chupar, which is of imitative origin (a sucking sound), is also found in the legendary monster, the chupacabra, which literally means "goat sucker."
The other suggestion is that is the Hebrew chupar comes from an altered version of the adjective meshupar משופר - improved. This supposedly began in the Israeli army before the Six Day War, where the soldiers were served manot krav meshuparot מנות קרב משופרות - "improved battle rations", which the soldiers shortened to mechuparot מצ'ופרות, and from that adjective the noun chupar arose.
Another related slang word that came out of the Israeli army is shaptzer שפצר. This root is a combination of שפר - "to improve" and שפץ - "to repair". Together, shaptzer means to repair and improve - i.e. "to renovate."