Q: Can tops get HIV from getting sucked off?

A: Getting and/or giving a blowjob is low to medium risk, but the risk increases if there are small cuts or scrapes on the cock, or if the mucous membrane in the piss-slit comes into contact with the mucous membrane in the back of the throat. HIV loves white blood cells and since there is a higher concentration of white blood cells in the back of the throat (and in mucous membranes in general) there's a possibility that it would make it easier for the virus to enter the bloodstream there.