The word, meaning HIV-positive semen ejaculations, first started on a gay men forum, where the users wanted to find HIV negative people and infect them. While this is serious and they shouldn't be doing this, it is very funny to hear them talk.
Semen containing the HIV virus; often sought by "bugchasers" and given by "giftgivers" who feel that contracting and giving the HIV virus is inherent to the homosexuallifestyle.