"Droid" is the default notification sound for the phone. Go into your main settings menu, then Sound and you should see a item for Default Notification. If it says "Droid", you can change it to something else if you want. Also, next time it happens, pull down your notification bar and see what notifications you have as many apps have their own settings for notification ringtones. Then look at your notification ringtone settings in each app and you should see one of them that has "Droid" or "Default Ringtone" listed. If you change to a different ringtone, it's still going to make the new ringtone whenever you get a notification for that particular app though. If you don't want the sound to disturb a meeting, then you should just put your phone on silent or vibrate or go into Sounds in your main settings and adjust the Notification Volume setting to a lower level.