Sentence:  Every now and then somebody on the alt.tasteless line mentions a certain perversion known as "<WSD>squicking</WSD>" which I assume is an urban legend. This act is similar to skull-fucking (intercourse with the socket of somebody's empty eyesocket, another act which I assume to be an UL), but instead of plucking out an eyeball, the perpetrator trephans the skull and thrusts between the hemispheres of the brain (incidentally killing the recipient). 
Meaning of the word marked with <WSD> tags:  To sexually penetrate a disgusting part of the head, such as an eye-socket