The hell do you think this is, West Side Story? Somehow I don't see Crips running to their local Hobby Lobby and buying all the blue chalk they can carry.
OK, it wasn't my best idea. But the only people I have seen doing this weren't what I would normally think of as Crips- they were at most 14 or 15 year old kids who are still afraid of being slapped by a parent. I'd need to be convinced that the person making the Crips mark on the back wall of Lantmännen Unibake isn't some even more ridiculous person than a Crip, ie a poseur Crip. I'm pretty sure the wispy waspy kid with his dorky lookout making the crown and some stupid nickname isn't actually a Crip.