Son I'm afraid your father is now a werewolf. We are going to need a silver bullet to kill him.
What makes you think he's a werewolf.
Crescent moon last night. Didn't you ever notice your grandfather is a frankenstein and your grandmother is a vampire? Didn't you take MUNSTERS 101 in school? THEY DON'T TEACH YOU KIDS ANYTHING!
Well lets go find some silver. We can just melt something down.
A teenage son should melt down into just enough metal.