It’s not surprising if your cheeks turn red when you realize your fly was down during a work presentation. Or that your stomach drops when you accidentally “like” your crush’s years-old Instagram photo. But there are plenty of day-to-day moments that feel really embarrassing for less discernible reasons — and it’s a topic that’s come up again and again on social media.

Commonly cited examples include things like people singing “Happy Birthday” to you, carrying a lunch tray, crossing the street while stopped cars wait, or someone holding the door open for you when you’re still far away and having to jog up.

Why do these seemingly innocuous moments tend to make people so uncomfortable? According to clinical psychologist Ellen Hendriksen, author of “How to Be Yourself: Quiet Your Inner Critic and Rise Above Social Anxiety,” many of them trigger self-consciousness — or “an uncomfortable awareness of oneself.”

“The self-consciousness might arise because we are the center of others’ attention, like having ‘Happy Birthday’ sung to us or having someone hold the door for us,” she told HuffPost. “Or it might arise because we are intensely focused on our own actions ― and possibly trying to avoid an embarrassing scene where we will become the center of others’ attention ― like carrying a lunch tray or making a plate at a party.”