Sentence:  The operation of <WSD>blockheading</WSD> is much the same as that of beheading, which Charles I underwent. In both the head is severed from the body. The body goes around without benefit of head.  The victim becomes a Headless Horseman, or that more common figure a Headless Pedestrian. In our day the operation is often done not on an executioner's block but on Paradise Avenue in Suburbia Manor. 
Meaning of the word marked with <WSD> tags:  To behave in a stupid manner.