That clever new phrase, naming an action that has occurred ever since the first cameras. You have all seen it, (or done it), are setting up your friends/family/children/spouse for a nice picture. Then just as you release the shutter, some hooligan, whether known to you or not, jumps in behind them and gets into the picture. When I was kid, it was nothing more than using two fingers to give somebody "Rabbit Ears"
As you can guess, I shoot a very large number of images, and every now and then I get that one image that meets the "photo bomb" description. In most cases, I never see it happen, only finding the results once I am back at my desk reviewing the shots. In nearly every case, the offending creature (bird, butterfly, fly near the lens, falling leaf) is badly out of focus. But, every now and then, I get that one photo bomb that is just fun...Last weekend, I captured a great shot of a Greater Roadrunner, perched atop a cactus. A cactus Wren took exception to the Roadrunner being there and dive bombed it several times. I stopped shooting as the Roadrunner was turning around and avoiding the Cactus Wren. Not the best pose for my Roadrunner photo. Some how I did manage to capture the wren, just after it returned back to it's perch.
I am just sure I heard the Cactus Wren calling..."nee neer, nee neer, nee neer!!