Summarize the following:
This method is more subtle than shining a bright light around, but it also requires that you are much more precise. If the laser-point slips away from the lens for even an instant, the camera will catch your face. Act quickly and efficiently to avoid detection.  This method should work day or night. It may be somewhat more effective in the dark.  You can use any standard laser pointer here. In general, the stronger the laser, the more powerful the blinding effect. The camera can see you until you get the laser aimed correctly. Anything that comes between the laser and the camera will instantly un-blind the camera. Also, the effectiveness of this method is a bit hard to gauge. From your end of the camera, you cannot tell if the laser is aimed correctly. Do not point the laser into your eye. You might blind yourself! Consider wearing dark glasses to protect your vision, but do not expect them to keep you completely safe. The focus required of this method means that you can only blind one camera with one laser. The laser is more subtle than LEDs or a flashlight, but the effect is limited. If you need to blind multiple cameras at once, then you'll need as many lasers as there are cameras. Consider coordinating with friends.

Summary:
Point an infrared laser directly into the lens of the camera. Be aware of the shortcomings. Look out for other cameras.