The U-Shirt, originally made of lamb's wool and called a Ewe-Shirt, was an immediate hit when invented by St Ignatius of Antioch during the Fifth Dimension's Third Final World Tour.
Alas for Ignatius, once the first rain fell on him in his new U-Shirt (while wrestling with demons on a side-trip to Albania), the U-Shirt shrunk when it dried in the warm sunlight and he choked on the turnip he had been munching on.
This invention went unnoticed for several millennia until the company that invented and patented the Happy Smiley Face acquired the T-Shirt franchise in West Muskegon in a hostile takeover started by labor strikers and sweet potatoes, don't ask.
The rest is history. (see Bernard Kludger's definitive biography of T-Shirt inventor Maxwell Parrish: "Maxwell Parrish: the Art of the Deal."