What is a Hob Knocker?

David Archuleta was a guest last night on ICarly, and was called a "Hob Knocker," which the girls explained is really nasty, and wouldn't say what it was on camera except that it was illegal!

Even David himself didn't know what it meant, as he writes in his blog: "Tonight on iCarly, the character Wade Collins called David Archuleta a “Hob Knocker.” Like David, I did not know what a Hob Knocker was, so I did a little research. It wasn’t as easy as I thought it was going to be; there isn’t much info out there on Hob Knockers, lol."