We learn in chapter 7 that Zigzag, whose real name is Ricky, is a blond camper (inmate) with a long neck and frizzy hair that stands up on end as if he has had an electric shock. Stanley thinks Zigzag is strange and calls him the "weirdest dude." Zigzag is strange not simply because of his looks, however, but because he is violent.
For example, Zigzag hits Stanley on the side of the head with a shovel after Stanley finds the lipstick tube and gives the lipstick to X-ray. Zigzag strikes Stanley so hard with the shovel that he falls down:
He [Stanley] wasn't sure if he passed out or not. He looked up to see Zigzag's wild head staring down at him.
Zigzag's strange behavior includes not apologizing for whacking Stanley. It is as if he has no remorse—though at the end of the book, he does say he is sorry.
Zigzag also appears to be paranoid, but he is not. When he says that the Warden has hidden cameras and microphones watching and listening to the boys, he is right.