Sometimes, there are things about me that even close friends and family end up surprised about, though I don’t take pains to hide it.
For example. in high school, my closest friend was a gay guy who I shared all my deepest secrets, desires, and dreams with, and he with me. We were inseparable. However, one night, he called me up to ask if I wanted to go out, and I told him to give me about an hour and a half, as I was busy trying to finish something up. He could hear noises in the background, and finally he asked, “What are you doing?” I told him I was baking a cake.
“A cake?” he asked.
“Yep.”
“Is it someone’s birthday?”
“Nope. Just felt like it.”
“Did… did… did you make it from a box mix?”
“No, from scratch. My mom’s recipe.”
“You… you know how to cook?”
From that day forward, he called me a little domestic diva. I invited him over to make sacher torte with me, so he could see for himself. Since we didn’t know how to pronounce “sacher torte”, we decided to call it “sashay tortay” and sashay we did, around the kitchen, singing it to the tune of RuPaul’s “Supermodel” (which was a popular tune of the time). 
But it was so odd. We’d been best friends for six years, and not until that day did he realise I not only knew how to cook, but I was a pretty damn good cook. He said I just “didn’t seem like the type”. Hmm.
Not a surprise to Dopers, but many are surprised to find out I like video games, and more specifically, role-playing games, and even more specifically, MMORPGS. Seems to blow people’s minds. I’ve gone into game stores alone, picked up an Everquest expansion, and have the clerk look at me (noticing my wedding ring) and say, “I hope your husband enjoys it, and if there’s any problem, tell him to bring it back, blah blah blah.” Sometimes I correct them, sometimes I don’t. I’ve heard, “Wow, I didn’t know real women played this game. I always thought the female characters were just dudes messing around.” To those ones I say, “Yeah, but I usually play a male character” (I don’t, but I like to mess with their heads a little).
The one artist in my CD collection (full of Blur, Pet Shop Boys, Air, Stereolab, Assemblage 23, KMFDM, etc) that gets the most attention and the most surprised reactions: Chaka Khan. I loooooove Chaka Khan. She’s not a “guilty” pleasure, and it’s not something I hide, but it gets the most “huh?!” reactions. My own mother was surprised just last week! I said, “Mother, seriously, you don’t remember me blasting “Ain’t Nobody” and dancing around the house to it all the time?”
Maybe it’s because I can’t dance, and I can’t really sing, either, so maybe she was just trying to block out the embarrassing memory. 
Still, Chaka Khan is the one artist who gets me the most :dubious: looks. I often get “you don’t seem like the type who’d like Chaka Khan.” What the hell type is supposed to? I thought everybody loved Chaka Khan! (and if they don’t, they should!) 
[sub]My husband was also surprised to learn this, however, it was pleasantly so, and now we happily listen to Chaka together. [/sub]
Okay, now it’s your turn: What things about you that are part of your normal life tend to surprise people, sometimes even those close to you?