Alright, here's an idea for you. Using only items you have in your home right now, try to build a rocket capable of lifting off vertically under its own power. If you happen to have actual rocket parts laying around, you cannot use them. Improvisation only.
Now, if you aren't at home, or don't feel like building it, you could also suggest plans for how to go about building it, using what you know you have at home.
I tried the other day, using a pen, the pen cap for a diverging nozzle, and hairspray. Either the rocket was to fuel rich or the choke point was too large, because it burned merrily until the whole thing melted, but never budged.