There are so many different forms of motorsport which could adapted to trolleys. Lets start with the simplest of them all; drag racing, I'm sure at some point you've found a perfect empty aisle taken a monumental run up, then jumped onto the wheels to experience exhilarating faster than walking speeds. More experienced trolley racers will be able to control a trolley with heavier load of shopping, simple things like turning corners and stopping become more a lot more difficult, controlling the natural oversteer is a skill mastered after numerous trips to the shops. Some of the wannabe Ken Blocks take advantage of the oversteer and drift around between the aisles narrowly missing the shelves. To make the most of this new motor-less sport, find yourself some mates, or challenge rival shoppers in true Fast and Furious style, and map out a route from the entrance to the checkout. If you want to raise the stakes, why not race for pink slips by betting on your shopping.
As with all forms of motor-less sport, trolley racing comes with its dangers; beware of the metal tins of chocolates or bottles of beer usually stacked up in a blind spot between the aisles, you could cause some serious damage to yourself. Always begin with a trolley loads you can handle; too light and you might pull some wheelies, too heavy and you'll loose control and end up in the reduced items bin. Remember there are hazards such as old people hogging the aisles, or people in coloured uniforms pushing really big trolleys at horrendously slow speeds, so be prepared to stop quite hard. Last of all you will almost certainly be on CCTV, so if you are really nice to the race marshals (or security guards as they are normally known) they might let you keep the video.
Good luck!