Carefully Done

My sister seemed to be getting a bit too confident on the lawnmower (which was left at my dads new house when he moved in). I've never been on it before, so she decided to show off on it, which didn't go too well when she started the engine suddenly, and flew down the garden at about 20mph. Even though it looks great fun, I'm too scared to go on it in case I go through a hedge or something, which is probably inevitable.