Gerald Herbert/AP Photo

This was no subtle chew, or light mastication. It was full-on chomping. Watching the Inaugural Parade from the presidential reviewing stand Monday, President Obama worked on what appeared to be a wad of chewing gum.

Caught by cameras for all to see, Obama furiously chewed as he waved to the floats and marching bands passing by, chatted with his family and danced along with the music.

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The president, a former smoker, is known to chew nicotine gum to curb cravings. In the past year, he has been seen several times chewing gum in public and packets of nicotine gum have been spotted in the Oval Office.

It's unknown whether the president was chewing the nicotine replacement Monday or just regular old gum but, either way, it sparked a fury of comment online.

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While some objected to the gum smacking as unsightly and inappropriate, it also offered a rare look at an unscripted president.

The gum-chewing came at the end of a long, formal day, full of pageantry and tradition. Sitting in the reviewing stand alongside his wife and two daughters, who were spotted playing on their phones, the public saw a more casual, relaxed first family.

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Sasha and Malia were seen snapping pictures of the parade, silly self-portraits and photos of their parents sneaking a kiss. The first lady grooved along to the music. And the president checked his phone a time or two.