This shirt is something that every fan to have, even once throughout his life. Dragon Ball is much more than a manga, it is a bridge between generations.
Kame-Sen'nin is a word game between "Kame" (turtle in Japanese) and "Sen'nin" (which can be referred to as a hermit or goblin). Among the fighters he was called as the great Muten Roshi. The word Muten is composed with the characters for the military and Roshi means "master" in Chinese.