The term originated in Iloilo City, Philippines. It means using the funds of one candidate to benefit their rival canditates. Turning one's own political contributions against oneself by deception and giving the contributed funds to a rival candidate(s). A double whammy.
A more polite way of saying "slut"; remember that a whore gets paid while a slut does the same work for free.
From SNL parody of Girls:
Jessa: I had sex with a cab driver, alright? It's called being free.
Blerta: You are prostitute?
Jessa: No, it's not prostitution if you don't get paid.
Blerta: You are UNPAID prostitute?!? You are lower than dog!