When a Runescape warlord takes lead and completely destroys your carefully sculpted pile, reducing it to 30 options spread across the face of the wilderness within a few minutes. Much like a fat ginger kid would step on your sandcastle when it is almost complete.
Leftover food stored in a plastic container that causes the food to hold the shape of the container when it is dumped out, much like when you make sandcastles with a plastic bucket.
When Banging a girl from behind and on the beach. You spit on her back just before you blow your load and as she turns around you blow it in her face then throw sand in her face and call out,"Sand Csstle Biatch!"