Q wearing shorts
Shorts, or short pants, were a type of short-legged pants worn in recreational or warm environments.
In 1986, a Human male jogger wore shorts while jogging in Golden Gate Park. (Star Trek IV: The Voyage Home)
In 2367, Q wore shorts as part of an archaelogical costume when suggesting he take Jean-Luc Picard to the ruins at Tagus III. (TNG: "Qpid")
The final draft script of TOS: "The Corbomite Maneuver" describes James T. Kirk as only wearing gym shorts while taking the exercise test as part of his physical. In the filmed episode, he is instead clad in his uniform pants.
In 2381, Lianne wore short shorts while working in the Boimler family vineyard. (LD: "Grounded")