The phrase "My hovercraft is full of eels" has become an internet meme and a common response to unusual or unexpected statements. It was originally spoken by the character Professor Farnsworth in the animated television series "Futurama." The professor had been asked about his favorite animal, and he responded with this phrase, which was then explained as being metaphorical: "It's an idiom. I wouldn't really put an eel in a hovercraft." 

As for its origins, the phrase itself is from the 1975 British novel "The Hitchhiker's Guide to the Galaxy" by Douglas Adams. In that context, it was used to describe how the protagonist Arthur Dent filled his ship with eels to protect himself against an enemy. The phrase has since been adapted and reused in various forms of media and internet culture, often as a humorous way to acknowledge confusion or surprise.