I usually speak around the 5th-grade level, with various dialects and slang and a bit cursing. Also, idioms, poetic speech, patterns, that sort of thing. And speaking in intentionally-wrong grammar.
More funner.
Another thing I do, to keep myself entertained, without losing my audience, is use a lot of metaphors and similes. They're like audial memes.
I tend to not debate or argue with anyone IRL, unless they're unusually confident and quick-witted.
But I write however I like. I need some outlet where I can just say precisely what I mean and where I don't have to pretend to be vapid and avoid confrontation.