Something I've never been too comfortable with is expressing myself in an overt sexual way. I can talk about sex quite openly, even having long conversations about sex-ed and offering tips and advice. I like porn and so on, but there's still a sort of barrier in my mind from, say, going to a fetish nightclub, or having sexual artwork made (since Sci is my direct avatar).
I think it's because when someone becomes expressive about their own sexual identity, people tend to focus on it, and I'm a lot more than just someone who's into kinky-XYZ.
(That's a representative note, btw, not "Sesame Street XXX". Though the number 7 is totally asking for it.)

I'm mulling over the idea of making an extra avatar specificity to represent and explore kinks/sex. 'Cos I'd like to try drawing porn, and know intellectually I shouldn't be shy to express myself. So I'm thinking up a new avatar. A few things have come to mind so far. "Inverted colours from Sci, but with flames" seems to be most prominent in my head right now, even if it's a touch simple. But who doesn't like amateur raver porn?
Feels like it might be separate enough from "me" to make it comfortable.