How to drag an item behind the vehicle in Mario Kart Wii

mario-kart-wii

I saw this in some player's YouTube video. They can drag a shell so that they don't get hit by other people's red shells. How do I do this?

You just hold down whichever button is normally pressed for shooting the item.

As soon as you release the button the item will then fire, and as far as I know you cannot stop holding the item behind you without firing.

This works with single shells, single bananas and possibly the fake power-up boxes.