In the Star Trek: Discovery episode "Lethe", Burnham and Tilly wear workout clothes that have the word "Disco" on them.
Why is this? This is the first time I can ever recall of anybody in Starfleet wearing branded t-shirts (seems that marketing went away along with money in the 23rd Century). And promoting a "late 20th century music trend" seems like a really odd choice, despite the future's fondness for our pop culture.
Why are Burnham and Tilly wearing "Disco" shirts?
EDIT: I feel like an idiot for just now realizing that "Disco" is probably short for "Discovery", but I think the question remains: why are they wearing these shirts? We don't see Kirk or Picard's crew wearing "Enter" t-shirts in their off-hours. Why wear t-shirts with logos that are shortened versions of the ship's name, when that is so contrary to every other example we have of 23rd Century fashion?