The act of removing a sister from your life, either physically or metaphorically. First used in the Simpsons episode "My Sister, My Sitter".
Simpson? Look, we've already been down there tonight for a sisterectomy, a case of severe butt rot, and a leprechaun fight. How dumb do you think we are?
When she finally divorces the bloke. A particularly difficult divorce from a very entangled relationship. A clean surgical break from a male spouse or partner from which the prognosis for recovery is improved functioning.
Judith finally underwent that desperately needed misterectomy. Too bad her HMO won't cover it.