onItemRightClick - displayGuiScreen(new GuiPNJ(entity2))

    @Override
    @SideOnly(Side.CLIENT)
    public ItemStack onItemRightClick(ItemStack itemstack, World world, EntityPlayer player) {
        Entity entity = Minecraft.getMinecraft().objectMouseOver.entityHit;
        if (entity instanceof EntityMarketPNJ) {
            EntityMarketPNJ entity2 = (EntityMarketPNJ) Minecraft.getMinecraft().objectMouseOver.entityHit;
            Minecraft.getMinecraft().displayGuiScreen(new GuiPNJ(entity2));
        }
        return itemstack;
    }