What exactly does 媽个八子 mean?
Well, I agree that @NS.X said. 

First, it should be "妈了个巴子", not "妈个巴子". 

Second, it is much worse than "他妈的". 

Actually, if you are angry with something, you can say "他妈的", to express your dissatisfied emotion. But please do not use it to a person. However, please do not use "妈了个巴子" even if for a thing, since it is too coarse. 

Anyway, it is not good to say these kind of word in China. Others may look down on you.