Originally Posted by Libertine

Complete bullshit.

First, remember that the size of the HIV virus itself is unimportant. As long as the fluids that carry the virus don't get through, you're pretty much fine.

Second, even if minimal amounts of the carried fluid and thus the virus would get through, this would still greatly decrease exposure, up to the point where infection would be extremely unlikely. Remember, even unsafe vaginal sex with someone who is HIV-positive gives a fairly small chance to get infected (especially for the man), so decreasing exposure a millionfold would naturally be pretty damn beneficial.

Finally, there is plenty of research on HIV-discordant couples which clearly proves that condoms are extremely effective. Anyone who doubts this should take a moment and google it.