1. Snaking
We used to do this all day in high school. Join the cool kids revolution.
In Mario Kart DS (and Mario Kart Wii), the fastest way to get around a track is to exploit the speed boosts that you get when you drift. By constantly alternating left and right drifts, you would move forward in a zigzag at a faster pace than you would without the boosts. It's called snaking because you move like an extremely fast snake, but at the same time, YOU'RE DRIVING LIKE A SNAKE. If I were Mario, I'd outlaw snaking and make sure that you lose your MarioKart driving license if you're ever caught boosting your kart on the road.
