When finishing up sex, you kick the shit out of your partner, as you would a sandcastle when you are done building it.
I sandcastled the shit outta that girl last night.
Another term for A member of the male anatomy, or his penis.
His gens, His shlim shlam, his wiggle tugger, his wenis
Marc: Another penis picture post... never gets old.
Lil: Oh wow that was a penis? I thought it was a sandcastle.
Marc: Omg lmfao
Lil: see? his hand looks like the sand.
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.
"I made too much spaghetti last night. I'll be eating sandcastles for days."
When taking a poop, of such that it is like wet sand, it piles up like a sand castle above the toilet water.
*Leaves sand castle in toilet*
Guy 1: "Who sand castled the toilet!"
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!"
I had to "Sand Castle" that biatch to get her off these nuts.