One of the great things about purchasing your meat as a whole animal and cutting it yourself (besides getting high-quality ethically produced meat for a fraction of its farmers’ market price) is that you have total control over how the meat is divided.
I’ve written about this before (Alternative Pork Primals) but I have another great example of an unorthodox meat-cutting practice: arm of lamb. While lambs have four legs, the traditional roast leg of lamb is always a hind leg. The shank meat is trimmed away, leaving relatively tender, lean meat that is best roasted medium rare.
The foreleg is a very different piece of meat. It could simply be billed as “foreleg of lamb” but I think we need a better way to properly distinguish it from the hind part. So I propose “arm of lamb”. 
The foreleg of lamb is typically broken up in the meat shop: the butcher uses a bandsaw to cut across the bones so that the uppermost part is left on the shoulder, the lowermost part is removed as a bone-in shank, and everything in between is trim for sausages.
You can, however, remove the entire foreleg in one piece. It looks rather similar to the hind leg, with the characteristic club shape, but the meat is completely different: tough and fatty, with several small, irregular muscle groups. So instead of being roasted at high heat to medium rare, the foreleg is best braised, or slow-roasted until it is falling-apart-tender, like a lamb shoulder.
I probably get a bigger kick out of this than most, but I like that it looks like a leg of lamb, but it is a braise instead of a roast.
Arm of lamb is harder to carve tableside, as it contains the shoulder blade, but the meat is tender enough that careful carving isn’t really necessary: if you cook the meat till it is thoroughly tender you can push a fork into the joint and pull and shred as much meat as you please.
- I’ll concede that “arm” doesn’t quite have the same appetizing ring to it as leg, and that it somehow even sounds cannibalistic. I suppose the reason is that legs are for locomotion, arms are for manipulation of objects; animals do not manipulate objects the same way humans do; their four limbs are used chiefly for locomotion; ergo they do not have arms; only humans have arms. That’s why is sounds weird to eat an arm. That being said, the lamb’s humerus is often referred to as the arm bone, and the sub-primal cut that contains the humerus can be called the lamb should arm, but these are technical meat-cutting terms that would never appear on consumer packaging.