The hindrance of the career of Arnold Rimmer...
Gazpacho soup (also known as gaspacho and gaspatcho), is a tomato and vegetable-based broth or liquid-foodstuff originating in the generally hot southern Spanish region of Earth, the homeworld of humans. Etiquette and tradition dictate that gazpacho is served cold, not hot.
By the time the JMC mining ship Red Dwarf went out on its last voyage, gazpacho soup was considered formal cuisine amongst the officers of the spaceships of the Space Corps. The soup was also a considered a delicacy of Red Dwarf captain Frank Hollister.
Captain Hollister once invited Arnold Rimmer, the Second Technician in charge of Z Shift, to such a formal dinner in the Officer's Club. As noted by Rimmer in his diary, in fact the only entry in it, "Gazpacho Soup Day" was on November 25th. Rimmer jumped at the chance as an opportunity to worm his way with the officers somehow, perhaps even get a promotion in the field, since he had failed his astro-navigation exams 14 times.
Rimmer turned on the charm (as much as Rimmer could, being Rimmer), but however was unaware that gazpacho is meant to be served cold. Rimmer loudly complained to the kitchen staff about it being cold, ordering it sent back to be reheated. With the captain, all the officers and the chef laughing, Rimmer thought that they were laughing at the chef, but they were actually laughing at Rimmer.
An embarrassed, shamed and horrified Rimmer believed that this event caused him to not receive a promotion, hindering his career and holding him back as a failure. When the radiation leak that killed the crew happened (actually caused by Rimmer's ineptitude), Rimmer's lasts words were "gazpacho soup", which Dave Lister watches as a recording.
Rimmer's clone hologram mocks the primary hologram Rimmer about the incident, which the primary Rimmer says is the most hurtful thing he could have said. Under the belief that he is about to be deleted as a hologram, Rimmer tells Lister about it. Lister deletes the clone and tells the primary Rimmer that he won't mock him about it, saying "souper" instead of "super". (Me²)
Behind the scenes
The whole "Cold Soup" business was actually based in a similar incident for the writers: Doug Naylor was served a bowl of cold soup once and was about to complain, but luckly Rob Grant was there to explain that some soups ARE served cold.