So Vincent and Mia eat and talk and dance and flirt, and then he heads back into the danger zone of her home, where she does a sexy dance to a Neil Diamond cover. (Back in junior high I once got to second base while listening to UB40's "Red Red Wine," so you better believe that's a powerful aphrodisiac.) Anyway, luckily for Vincent, instead of jumping on his manhood, Mia just does lots of heroin and almost dies.
The Not-Sex Scene:
While not quite as bad as screwing Marsellus' wife, Vincent knows that letting her die would also be kinda bad, so he enlists the help of his drug-dealing friend. It's soon determined that the only thing that can save Mia is a shot of adrenaline right to the heart. So yes, Vincent totally penetrates Mia and makes her scream, but not with his penis -- with a hypodermic needle penetrating her breastplate and entering directly into her heart.
In many ways, the scene mimics the classic sexual overtones of stake-driving in vampire movies. A phallic symbol, penetration, screaming, and blood. All the visceral parts of sex in a memorable scene where no one get laid.