the vajalien probe
The Vajalien Probe occurs when one is giving slightly over-enthusiastic oral sex to a female partner, leading to their nose and mouth become engulfed in their partner's vulva. The final result gives an appearance that they are being facefucked by a monster from Alien.
Man, I am never giving Stephanie head again: she gave me The Vajalien Probe last night. I thought I was gonna puke out a Xenomorph.