To whom did he say that? the ref?
Anyway, that's Pique being Pique and a Barcelona player. They always say nasty thing about Madrid, but no action is taken.
http://www.barcablaugranes.com/2015/8/18/9169313/pique-miss-la-liga-debut-four-game-ban-referee-insults
EDIT:
Gerard Piqué's insults to the
assistant referee during the Spanish
Supercup could mean a bigger
punishment than just a red card.
At the begining of the second half of
Monday's 1-1 draw, the Barcelona
star center-back complained about
a missed offside call by the assistant
referee. According to the linesman,
Piqué got so mad he said: "I sh*t on
your f***ing mother!", which
crossed the line so much that it led
to a red card.
Because this was a domestic
competition, the Spanish Federation
uses the same criteria as England:
the one-game automatic ban is due
on the next domestic game,
regardless of tournament. That
means Piqué will miss Barça's
debut in La Liga, which is a third
straight date with Athletic Bilbao,
Sunday at San Mamés.
However, the LFP will do further
investigation on the issue, and
there is a chance Piqué gets a four-
match ban for his actions, which is
the maximum punishment for
insulting a referee. If this happens,
the Spanish international will miss
the first three league games of the
season.
We'll have further info as this
develops.
According to mirror