Geez–I’m having trouble thinking of anything about me that shocks anyone. People seem to get an impression of me that’s usually right on the money.
Sorry to be so dull.
People are often surprised that I’ve got a nerdy, brainiac personality. I look and sound more like the stereotypical jock/fratboy (even though I hate most sports and don’t belong to a fraternity).
I could also pass for a teenager, and I can’t recall a time I’ve bought alcohol without being carded. I’m almost 28.
People are always surprised to learn:
that I am closer to 50 than 30. I don’t look 47. Last week, someone said he thought I was around 32, and was shocked to know that I started working in the business before his parents were married.
I don’t know how to drive and have no desire to learn.
I was essentially destitute and sometimes homeless for over a decade.
I can play guitars, bass, keyboards and drums with equal facility (at a reasonably high level of proficiency).
…and that I’m the voice of that guy they hear on the radio several times an hour, every day of the week. (Oh, I expected to see a guy in a tuxedo!)
I would bold “long hot-pink manicured fingernails” but I think it’s against the rules, so just bold it in your mind and we’ll consider it a done deal. I can’t be held responsible for your mind-bolding! 
Marge: um, really? And they don’t have potential sex partners running away in droves? Ow.
As for things about me that often surprise others…lemmesee. Do the tentacles count?
I’m Caucasian, and my wife is Chinese. “Interracial marriages” are not that common here in the Midwest, so I occasionally get the “Oh!” response when someone first meets my wife.
But what really blows their mind is when someone finds out I started a militia group, and enjoy shooting .30-cal assault rifles and stockpiling ammo.
I have the opposite problem of many Dopers. Everyone assumes I’m a slut/hippie/floozy type because I look like it. I use this constant misunderestimation to my great advantage and pleasure.
fishbicycle yours is a life story I want to hear. Have you posted about it here? In great detail? If not, please do, dear, because the sketchy details you provide are tantalizing!
Thanks! I’ve posted a fair amount about my life, but I leave out a lot of stuff because I just don’t want to talk about it anymore, it used to be such a drag. And I don’t come here to complain or look for sympathy, so I don’t rabbit on about my crappy earlier decades. A poster asked one time what it was like to be homeless, and I responded to that. If you want to do a search for posts by me, I won’t feel like I’m being stalked! If you had any questions, you could e-mail me. OK?
People are surprised that I can be girly. Apparently just because I walk like there’s a penis between my legs, and I don’t wear makeup, I’m not allowed to like wearing skirts or doing my nails. Or giggle.
Thanks fishie. I understand. 
That poster could have been me. (Sometimes I’m not very good at remembering who said what on this board!) I’ve tried for a long time to understand homelessness and have posted to/started threads addressing the issue.