I have muslim friend and he said bad words against the pigs what is the reason?

It is a misunderstanding. Muslims are required to be kind and having sympathy to all animals and God creatures. If pork is forbidden to eat per Islam (and Judaism) teachings it does not mean to be cruel to pigs. Remember that a prostitute offered water to a dying thirsty dog by getting water from a well in her chose and allowed him to drink then God forgave her and accepted her in his Paradise; as narrated by prophet Muhammad (PBUH).

shia*

It is not allowed to eat pig in Islam. but other things are not so acceptable.