My speech often slips between various accents/styles between sentence fragments. One reads/sounds like modern slang, the next rather Shakespearean.
The other, and more readily obvious thing, is overuse/slight misuse of slash marks to combine/offer a choice between two or more things.
e: Oh, and I definitely overuse "also" and "anyways". There's also an interjection that we started using at my middle school that's spelled "uh-buh". It's kind of a rebuke? Basically no other word really fits the emotion so I still use it often. I use lowercase i if I'm feeling really guilty or sorry. Sometimes I start speaking in Spanish for no reason (I'm not horrifically annoying to talk to no shh).