It's an annoying fact that power tools don't stay plugged into extension cords. The plug-to-plug connection isn't strong enough by itself to resist the wear and tear of work. Twist locks work well, but if you want to use them you need to modify all your tools and extension cords with matching twist lock plugs. It's expensive, time consuming, plus you can't easily use tools with standard plugs anymore. Most people just tie a knot around the plug connection. It's fast, easy and it works. However, knots are bulky, often get caught in debris, subject cords and tools to undue stress and cause potential safety issues.
Finally an affordable solution to the extension cord problem -- Introducing, the CordSnake™. It's as easy as tying a knot, actually faster, really handy for ladder work, great for tools with short power cords, plus you can use it to keep your extension cord coiled up after use.