I designed Martin’s robes after a specific type of Japanese mendicant monk regalia. I considered adding the zigzag stripe usually on his t-shirt, but I couldn’t work it into the design properly.
The zigzag on Martin’s shirt wasn’t meant to be a reference to his distinctively shaped (ie: I didn’t know how to draw them when I started drawing) sideburns. It’s supposed to be a reference to Peanuts, which I think ties with Calvin and Hobbes as the second best newspaper comic ever. (Both of them are firmly beaten for first place by Footrot Flats, but that would be more difficult to reference on a shirt.)