Weapon Dog

"Mum? What's a weapon dog?" Simon shouted from the hallway.
"You know those ghastly boys who hang around in a big group in the park, the ones with the shaved heads and tattoos from the council estate? The dogs they have are weapon dogs." Simon's mother said.
"But why 'weapon'?" said Simon.
"Because they use them to intimidate people, it's the same as brandishing a knife."
"I see."
"And no, you can't have one."
"I've already got one, it's attached to my left ankle, there's a lot of blood on the carpet and I think I'm going to fein—"
*THUD*