Starfleet diapers
A diaper is a type of cloth garment, usually worn by infants, to aid in containing bodily waste.
Following repeated offers by Montgomery Scott, in 2369, to assist Geordi La Forge in Engineering, which ultimately resulted in La Forge telling Scott that was "in the way," the angry Scotty retorted that he "was driving starships while [La Forge's] great-grandfather was still in diapers." (TNG: "Relics")
In a similar vein, during their encounter in the Nexus, James T. Kirk remarked to Jean-Luc Picard that he "was out saving the galaxy while [Picard's] grandfather was in diapers." after the latter reminded him of his duty as a Starfleet officer. (Star Trek Generations)
In late 2377, Harry Kim gave Tom Paris and B'Elanna Torres a diaper, with a Starfleet emblem embroidered on it, as a gift for their baby shower. Kim claimed that garment was "standard issue." (VOY: "Human Error")