A verbal warning shouted at onlookers when an old person's story has begun to wander off. Similar to an Amber Alert, but different.
Grandpa: "Bears? You want to hear a story about bears? So I was driving out on route 6, just past the old red barn, which used to be green before they painted it yellow, which i knew because i used to pick raspberries in the field behind the barn, which used to be a corn field after it was a civil war battlefield, blah, blah, blah..."
Jason: "Silver Alert!! He's lost the point again. Quick, everyone look around and try to find it!!"
Grandpa: "and coming back to my original point, I choked a bear to death with my bare hands."