Is she hot? If so, just fuck her a few times raw and you probably won't catch anything.
^^ This
Also, immediately after the act if you jump off her and run out of the room, shave all your pub3s off, wash in unbearably hot water and splash cheap cologne all over, the sting will burn the VD off of you for sure. And I realise you like this girl but don't worry - if she's a keeper, the howl of pain won't scare her away...
Gotta do it immediately after spooging* though, the timing is critical - it's like the anabolic window, but for dirty c0cks...
*preferably during the self-loathing and disgust phaseDr Taf