The character gamma (extended SAIL ASCII 0001001), which with a loop in its tail looks like a little fish swimming down the page. The term is actually the name of a Chinese dish in which a fish is cooked whole (not parsed) and covered with Yu-Shiang (or Yu-Hsiang, or in modern Pinyin transliteration yuxiang) sauce. Usage: primarily by people on the MIT LISP Machine, which could display this character on the screen. Tends to elicit incredulity from people who hear about it second-hand.
Yu Shiang Whole Fish is alive and well in Unicode as U+0263 LATIN SMALL LETTER GAMMA (as opposed to the actual Greek letter at U+03B3, which usually has a loopless glyph; the form of U+0263 is consistently loopy). This symbol is included in Unicode as a Latin letter because it is used in the International Phonetic Alphabet. In the IPA, gamma represents a voiced velar fricative, the sound commonly transcribed “gh” in Arabic or Klingon.