Ur sister is a mister

An insult worse than than ur mum gay, ur dad lesbian, and ur granny tranny. This is the worst insult imaginable and there is absolutely no recovery from it.

Grant: ur mum gay
Mark: ur dad lesbian
Grant: ur granny tranny
Mark: oh yeah, well ur sister is a mister
Grant: *all veins inside body explode, has a seizure that causes him to pull out a gun from his jacket, and blow his own brains out.