Obviously the developers did not want anybody skipping massive portions of a track, so they created an intricate checkpoint system. This is a map of the checkpoints belonging to the track Sherbet Land. The blue lines show normal checkpoints, which are used to help Lakitu decide where to place you. Those are unimportant for now. The green checkpoints, however, are key. You can think of them as boxes that extend to the next blue checkpoint. The red starting line also acts as a green key checkpoint. In order to complete a lap, you must drive through all of the green checkpoints in order. If the game’s counter determines that you were in the final green checkpoint before crossing the finish line, then you get a lap and the counter resets back to zero. The glitch comes where if you are in region one, you can make it to region eight without going into the finish line. Therefore, you don’t lose a lap. In Sherbet Land’s case, you can do a wheelie to adjust the rotational value of your bike and have at least 5 frames of airtime to clip high into the air next to the finish line. If you land in the water, Lakitu will place you on the track right after region eight. If you then drive back to that region and then across the finish line, you get a lap. It looks like this: