I've just detected a misspelled "natürlich" — written like "natürlisch". Is it a mistake or slang/dialect?
If somebody writes “natürlisch” in a phrase like “FIFA natürlisch!” it's virtually certain that it was done intentionally.
It's such a common word that it is not likely to be spelled wrong by genuine mistake.
On the other hand the context let's you expect such kind of jokes. It's common to spell “natürlich” formally incorrect as “natürlisch” to hint at certain sociolects or even just to emulate the slurred speech of drunk people.