I am so aggressively not on twitter that I've recently wondered whether I need to create a Bitty account just to keep anyone else from grabbing it and people thinking I'm on twitter. Assuming nobody's taken it already, of course.
Might as well grab it. I've started grabbing my name in different places, even if I never plan to use it. It avoids confusion down the line in case you do decide to use the service. (Example: A friend messaged me saying he found a comment I'd made on a YouTube video. It wasn't me, but boy did it sound like me!)