Spock, the half-Vulcan science officer played by Leonard Nimoy in Star Trek: The Original Series, which first aired in the 1960s, became famous for judging human behaviour by logic alone. Illogical and most illogical were among his signature responses, delivered without anger or surprise. As Star Trek clips and reaction sounds spread online, that short verdict escaped its episode context and became a reusable shorthand. Fans and editors still use it because the meaning is instant, even for viewers who have never watched the series.