""casca grossa" means "tough skined" in Portuguese, and it is a common term in Jiu Jitsu and in the Brazilian culture, to describe someone who's tough in nature. Cezar Guimaraes started being called the nickname Casquinha when he was around 7-8 years old. He was one of the toughest kids in the class and as Casquinha is a friendlier way to say "casca grossa", like "little casca grossa" the nickname seemed very appropriate."