On Star Trek, before the actual cast would be sent on a mission, a minor character would be sent there instead and get killed to highlight the danger the actual cast would had to endure, because of the common colour of their clothing, these characters are known among Star Trek fans as redshirts.
On Futurama, these characters get a new meaning, especially under the command of Zapp Brannigan, who would often carelessly send his own men from the DOOP Army into a suicidal mission, noticeably, his men all wear uniforms in the colour red.
While the term "redshirt" has never been mentioned on Futurama, it has made numerous reference, such as the Battle of the Octillian System, in which Zapp sent waves after waves of his own men at the killbots, until they shut down when they reached their kill limit. But also the character Welshie in "Where No Fan Has Gone Before", who is quickly killed off by Melllvar in his anger.
- These are appearances where the joke occurs.