Snaking is a technique for experienced players that allows the user to continuously drift back and forth to perform Mini-Turbos on a straightaway. It was first developed as a byproduct of online competition in Mario Kart DS, though the technique has been available since Mario Kart 64.
The technique is essentially a chain of Mini-Turbos. Snaking is easily done by lighter karts with extreme handling, mainly the Egg 1, Dry Bomber, and ROB-BLS. It is easily done on Figure-8 Circuit, which is why many beginning online players don't like this course. It is generally looked down upon to use the technique against unskilled or non-snaking opponents in online matches, but it is commonly used in Time Trials to achieve impressive records.
Nintendo has made snaking much more difficult in Mario Kart Wii and newer games, attempting to emphasize drifting, which was introduced in Super Mario Kart. However, it is still possible in Mario Kart 7, though requiring a bit of longer time and precise timing to do so.