What a man does (by stamping on it with his foot) after the blessings at a Jewish wedding, as a commemoration of the Temple in Jerusalem, which was destroyed in 68 or 70 of the Common Era. The idea is that even at the peak of our joy, we have to acknowledge the sadness and evil that persist in the world.
"Wasn't it a beautiful wedding?"
"Yes, they're just perfect for each other."
"I know. When he broke the glass, I cried."
Its when you play SOCOM II US Navy Seals and the other team pulls out either M79s, M203s (Grenade Launchers), AT-4 Heats, or RPGs (Rocket Launchers) and you tell your team this and pull out launchers as well.
"Shit they just slaughtered us with M79s... let's break the glass and pull out our M203s. We're going to fucking bomb these bastards!"