I could care less
This is what stupid people say when they, in fact, mean, "I couldn't care less." The intent of the phrase is to express the fact that the level of caring the user has is nil. However when taken literally, the phrase dictates that there is at least some level of caring and it is possible to care less. Some people have said that the phrase is used sarcastically and that people who use it know that the meaning is opposite to the literal interpretation. However it is far more likely that people who say, "I could care less," and mean the opposite are just stupid.
Example:
I could care less about your opinion.
I could care less about your opinion.