A Rolling Freight Cargo

Towing my green twist-tie forward, my wheels rolled across the floorboards until I bumped into a red plastic bottle cap resting upside down. It looked just like an open wagon waiting to be coupled. I gave it a brisk push with my bumper, but it slid sideways. So I took the hooked end of the twist-tie, backed up a tiny notch, and worked the wire loop under the bottle cap's ridged rim. With a cheerful hum of my motor, I chugged ahead. The cap slid right along behind me like a proper freight car carrying air.