Rather than using a cork try something with abit more grip. I did this 'experiment' when I was in high school, made one at home, brought it into school, got in the school paper. Got most of the class wet cause I told them to stay in close, the only wise one was my teacher who stayed back..
My last 'experiment' that I whipped up was a potato cannon.. looks very cool at night cause you get a 2 foot long blue flame belowing out the end..