It’s been 15 years since we lost our innocence. 15 years since two hijacked planes crashed into the Twin Towers of the World Trade Center, another dove into the Pentagon, and a fourth was downed in a field in Pennsylvania as the passengers overcame the hijackers.

The attacks left Americans reeling. We drew together then, lit our candles, honored the helpers and those who died helping. Many, many flags flew, all at half mast.

Today’s talk of patriotism isn’t related to this anniversary. Today’s talk is about etiquette: expected behavior toward the United States flag, the Pledge of Allegiance, and the National Anthem.

Here’s a summary. When the flag passes in a parade or the flag raises during a ceremony, people are expected to stand. During a parade, onlookers may also applaud. For the Pledge of Allegiance, those in attendance should stand and show the “citizens’ salute” of placing the right hand over the heart. When the Star Spangled Banner is played or sung, those present will stand. The hand over heart salute is optional. Applause is not necessary, but may be allowed.

Quarterback Colin Kaepernick quietly refused to stand for the National Anthem at a recent game. Unfortunately, a camera was on him, ensuring that millions of fans were watching, too. He explained that he knelt during the Star Spangled Banner to express his concern about social injustice in the U.S.A., in particular the systemic racism rearing its ugly head across the country.

When someone in the public eye makes a statement, verbal or symbolic, there will be reaction, strong and widespread. I’m not sure Kaepernick expected the firestorm ignited by his personal protest. He drew both criticism for being a spoiled rich guy and support for choosing a nonviolent manner of exercising his freedom of speech.

So here we are, watching NFL football, as much of the nation does on autumn Sundays. We’ll fire up the grill and dust off our cheese heads. And each time we hear the Star Spangled Banner before a kick-off, will we look around to see who is standing and who isn’t? Or will we listen quietly, mouthing the words, remembering the day the hijacking that shook our safe and innocent world?