You definitely CAN get HIV from receiving oral. We don't want a rumor to the contrary to take hold here.

And Lazy, the reason condoms cover the whole penis is that a cap alone wouldn't stay on during intercourse. Think about the forces and shapes at work there. A cap just wouldn't be safe enough. And it's not just the urethral opening that needs covering anyway. It's the entire penis. If there were a tiny, microscopic tear in the skin somewhere along the penis, that could be an entry point for the virus (or myriad other STD infections). And other STDs like herpes can inoculate the skin and not just the urethral opening.

I'd like to personally give that creep in the story a lethal injection . . . .