What is the (in universe) origin of Wally's Semme belt thing? Was it just some meme that Walky invested heavily into pre-college? Bought a bunch of shirts with the band "For the bit" but now just wears them unironically?

In this case, it's a hoodie that really exists that I saw in like Target or whatever which had a yellow stripe and was like, Yes, Walky Will Wear This

"But parent, I do not wish to wear the yellow stripe!" "Put the damn hoodie on Walky!"