Because think about it. You’re a bunch of (essentially) homeless wanderers who go around and murder people (or goblins, or orcs, etc) for profit. Hence, murderhobos.
Well, that deserves a gorram t-shirt.
And a coffee mug.
So I made it.
I’ve also got some other designs up there right now as well, like the imaginary spoons (men’s, women’s, mug), the cows are not as they seem (men’s, women’s), and my nod to how everything’s better online: this would be funnier as a gif (men’s, women’s).