The phrase "my hovercraft is full of eels" is a classic example of anti-humor, which involves saying something that seems funny at first glance but upon further inspection turns out to be nonsensical or absurd. Anti-humor is a form of humor that has been deliberately designed not to be funny.

The oddness of the statement itself, combined with the lack of context, leads the listener to assume it's a joke. However, once you realize there's no punchline coming, and eels in a hovercraft don't really make sense, it becomes clear this isn't meant to be humorous at all.

This phrase is often used in discussions about humor or cited as an example of something that appears to be funny but isn't upon closer examination. It's also become somewhat of a meme in online communities and discussions related to comedy.