うなぎ, as indicated in the title of this site, is from comedy show Friends, below is a preview of the origin of Unagi.
However, as a post from [http://wasa-bi.com] explained
Unagi is a Japanese word for freshwater eel and it is a common ingredient in Japanese cooking. Unagi is often served on rice and it is something expensive to eat in Japan.
The word he must have gotten mixed up with "Zanshin"(残心); a term used in Japanese martial arts. Literal translation into English would be "a remaining mind".
"Zanshin" refers to the state of total awareness and it means being aware of one's surroundings and enemies, while being prepared to react.
Friends is really great, and so is Japanese culture.