Vasodomy is an obscure word known only to those who practise it. As those that practise it are arrogant bald men with a control complex, it is indeed quite amazing that half the male population does not already know it.
Vasodomy is the act of a bald man, after placing butter (margerine will suffice if you're health conscious ) onto his bald scalp, using his lubed up head to anally penetrate another person. Some believe that the term arose from the little known Norwegian god Va, who was the god of baldness and sexual prowess.
Vasodomy is not necessarily the reserve of men, some women, Gail Porter for example, have the tools for the job.
It has been suggested that the true aim of Vasodomy is for the victim (the vasodomised) to be penetrated so hard by the attacker (the vasodomiser) that he is forced to cough up his own testicles. Vasodomy is not an act engaged in by consenting partners, no-one would actively want to experience it.
A derivative of vasodomy is known as Partial Unbirthing - click the link for a small NSFW video.