I thought it might have had something to do with There Wild Ones but only Lee Marvin seems to have strip top on, I thought they were a few more in strips but no. Hit the gonzadeath above subscribe takes u to channel page hit about in the top right send a message. He would be able to tell what its about. I have wondered the same thing myself, if u find out can u post it please.
In the party section of the video, there are several people with striped shirts too. I guess not all of them wear it on the outside while riding... I thought it was just a "japanese biker outlaw" thing, you know, striped clothing like prisoners sometimes have in old movies...