phone on vibrate
what happened
phone rang during a birthday party. embarrassing and avoidable. a sharp ringtone cutting through a quiet moment makes everyone look at you.
why it's a gotcha
you think you'll remember to silence your phone. you won't. and a loud ringtone at the wrong moment (during a presentation, a quiet conversation, a ceremony) is a small thing that leaves a bad impression. impressions are made of small details like this — the same reason how you introduce yourself matters.
the fix
choose a ringtone that's quieter and less sharp, or just keep it on vibrate at events. better yet, make vibrate your default. you almost never need a loud ringtone.