Crock Off

When used alone, crock is often used as a synonym for "lie" or "bullshit". But when paired with "off" the phrase can be used interchangeably with "fuck off". Because the phrase is relatively uncommon, it is a great way to tell your opponent off while also confusing the hell out of them and making them forget what they were talking about in the first place.

Ignorant peasant: "Hey guy, you got fake timbs boy!"
You: "Crock off!"
Ignorant peasant: "Huh?"