I am looking for a compound noun that has a meaning that is completely (or very) different from the words it is derived from. This because I want to give an example of how powerful the human brain is in understanding meaning from context. For example, we know that washing machine is a machine that washes. We know that a haircut is a specific way in which your hair is cut. These words are relatively easy to understand, because the meaning of the individual words is largely retained in the meaning of the compound.
I would like to find a word "X" in which the two seperate words are relatively well-known and have individual meanings, but when combined the meaning is completely different.