1. Speak English. Somehow they forget that me speaking English is like them speaking French and is actually not a talent, but every time I say something in English they admire my accent. Which is pretty fun, because I didn't think anyone liked American accents.
3. Sing. Going along with the last one, people here are so impressed when I know the lyrics to English songs. It does help that Belgians listen to a lot of American music so that they don't hear my attempts at French lyrics. But if you and a Belgian are singing along to the same English song and you keep going while they fade into indiscernible mumblings, chances are they will turn to you with their mouth open and ask how you know those words. Even when I say "I mean it's English..." they shake their heads and say "still."
3. Learn to French braid your hair. I assume that in the States we call French braids as we do because they are too tricky and fancy for us and so they must be French. Likewise for the Beglians (and French?); they call them "tresse africaine" because they're too tricky and foreign for Belgium. I wonder what they're called in Africa... At any rate, every time I french braid my hair somebody asks me if I've been to the hairdresser, even if it's a sloppy one. They always want to know how I learned to do it and I have to pull out the slightly-embarrassing story of how I wanted to one-up my sister, who could french braid her dolls' hair, and so learned to do it myself. And then to try to make them feel better I tell them that it's not super-hard (literally, they say "super" all the time here), it's just that your arms get tired and then you generally give up. Which is basically true.
4. Learn to shuffle cards. The other day at lunch, a girl I don't know came up to me and asked if I could show her how I shuffle cards. I did it for her, then turned back to my own card game to find that she was not the only one impressed. Whenever I shuffle cards they call me "belle gosse" (or beau gosse for the guys, basically what they call a really cool/goodlooking/talented person), or, even better, "Las Vegas." We're unfortunately never playing anything as cool as poker, so I can't whip out my shades and fancy vocabulary (not that I know it in French), but I still have fun with my Vegas nickname.
That's all I can think of for the moment. Next time anyone gets really wowed over my doing something simple I'll add on/make a part two. À la prochaine!