Watersports, in relation to sex, is used to describe pissing on someone. Pissing on someone carries no risk of HIV transmission. Piss does not contain infectious HIV so you can't catch it this way. There is no risk at all from pissing on healthy, unbroken skin but there is a risk of other infections, such as CMV (a virus in the herpes family) or salmonella if piss gets in the mouth or eyes. These infections may be more serious for HIV-positive people.