In supermarkets across Britain, the trolley jumper is becoming well known as an invasive species. If you’ve ever starting unpacking groceries only to find books nestled amongst the vegetables, you know you’ve been a victim.

These books have developed a buddy system. It’s generally considered just not safe to go it alone, so they pair up and jump in twos. Of course, there’s the occasional kamikaze loner, too obscure to find a match, that makes the leap solo.

Once they’ve made it into your trolley or basket, the books have a built in instinct to hide. They are especially fond of salad leaves and loaves of sliced bread which easily obscure them from view.

The checkout is a risky area even for the seasoned jumper. If the luck’s in their favour, the checkout attendant will be chatty and distract you as you unload your shopping onto the conveyor. If jumpers are spotted, the โ€œlook cute and appealing responseโ€ kicks in. How can you be so cruel to leave them on the side, destined to fall on the floor and be run over by a wonky trolley? No, I thought not.

Occasionally, the checkout attendant will catch your eye and give you a knowing look. They know it’s hopeless. Instead, they carefully wrap your books up to keep them safe and dry for the trip home.

Past the threshold, they can survive dormant for months, even years, before they reach their full potential. They don’t mind, it’s survival that counts.

* For US readers, trolley = shopping cart. The other kind of trolley jumping is too extreme even for these intrepid books!