One of the most offensive French insults. Literally meaning: "Go Fuck your Mother".
One doesn't have to know the person's mother or hold any grief against her to deliver the insult.
Presumably what Materazzi told Zidane before receiving a well-deserved head-butt during 2006's FIFA world cup.
Sale Batard, va niquer ta mère. (Dirty Bastard, go fuck your mother).