The Shirt, Khaki Fatigue, is possibly the second most hard-wearing item of issue kit going, after the Jersey Heavy Wool (I was still wearing a jersey that I'd nicked from my Dad's MFO box of Buckshee kit, so it had seen at least thirty years of service).
Also known as the "Shirt Hairy", it would make a man of any scrawny seventeen-year-old, if only by proving that uniform could make you suffer. After fifteen years ownership, mine had softened to the point where they were actually comfortable. Either that, or my skin had hardened.
Their other redeeming feature was that unlike the cotton shirt that replaced it, it didn't wrinkle and crease at the touch of a feather; and thus was just the business for those character building courses where Drill pigs and frequent inspections were a feature.
It could, of course, be made less irritating by the simple method of shaving any part that actually touched the skin.