I tend to think that I type in a somewhat well-mannered form, but I know that from time to time I sarcastically slip in ungrammatical phrases (or perhaps I'm using those phrases to show my sarcasm).
I keep my writing at a high level, so that my speech may also remain so. I've noted on many occasions how my speech is affected by my typing. Best example is the word "bro." I never used it, when speaking or typing, until it became associated with insulting (through imitation) a member of a forum I used to browse, and although the original phrase was "lolbr0," the word "bro" secretly crept into my vernacular.