Here's a tip I just learned last night:
If you have a citronella candle that has burned down, do not under any circumstances attempt to refill it with citronella oil when a replacement candle proves impossible to find. If you do, it will burn just fine the first few times but once the wick has burned down (impossible to see while it's burning) it will suddenly erupt into a towering inferno of flame at least 18 inches high! When your friend panics and pours hot water from the kettle on it (BAD idea - never ever pour water on an oil fire!) it will sizzle and spatter like a thing possessed. Once the flame is finally put out, you will still have boiling oil, that remains quite literally boiling for over an hour afterwards. And then, when it's all over, you will be left with this:
And believe me, you don't want that.
Stop by Rocks in My Dryer for more helpful hints.