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Kissing kids photobomb Obama

During his 2012 campaign, President Obama surprised students in Delray Beach, Fla., with an unscheduled stop to take a photo with the kids. But perhaps the biggest surprise of this photo op was the kissing pair in the back row photobombing the president. (@BarackObama/Twitter)

2012 Year in Review: Most viral photos

From the Harper wedding photobomb to the most retweeted photo ever, this slideshow takes a look at the most viral photos from 2012.