One time use headless bodies would be sold in one pack. Heads, with extra long one-time-choppable necks, would be sold in a different pack.
Bodies would be sold in packs of 5. Heads would be sold in packs of 4, requiring you to buy TWO packs of 4 to have enough heads to match the 5 bodies in that one pack and leaving you with 3 unused heads requiring the purchase of another pack of 5 bodies to consume the heads. Repeat ad infinitum.
One time use headless bodies would be sold in one pack. Heads, with extra long one-time-choppable necks, would be sold in a different pack.
Bodies would be sold in packs of 5. Heads would be sold in packs of 4, requiring you to buy TWO packs of 4 to have enough heads to match the 5 bodies in that one pack and leaving you with 3 unused heads requiring the purchase of another pack of 5 bodies to consume the heads. Repeat ad infinitum.