Voodoo is still practiced in parts of Africa. It's clearly what he means. He called Mido a gypsy too, so this is typical Zlatan.
You've clearly got it wrong.
Zlatan's the one being called a gypsy, by rival Italian fans and Swedes.
Mido? He threw a scissor at Zlatan at Ajax apparently, but there was no mention of any slur according to both parties.
As a Milan fan, I often get into arguments with people who like to praise Zlatan at the expense of the team. Zlatan IS an egotistical prick and bully who likes to undermine his coaches.
But how could anyone take Lukaku's side in this?
He's the one who started all this by starting a fight with Romagnoli and shoving Saelemaekers who was only trying to calm down his compatriot.
He even hit some Inter staff crew that were trying to ease the tension.
Zlatan said "Call your mother, do your voodoo shit. You little donkey".
Lukaku:
"I feck you and your wife bitch"
"I'll fecking shoot you"
"Son of a whore"
If you think Zlatan went off limits, or that Lukaku's behavior was justified then you're as incredibly dumb and infantile as Lukaku and will hopefully not reproduce.