My son has schemes and plans for everything, including a boys' club whose sole purpose seems to be to spy on the girls at aftercare and annoy them. And, I'm sure, compare notes, and sneak around, and form better spying methods, etc., etc.

For no reason at all, he wants his club to have a weapon of his own creation he calls a "Mazooka."

Me: What is that, exactly? What's it made of?
My son: Oh-- we just need two chainsaws, a torpedo, and a harpoon.
Me: (Big WTF!? look)
My husband: We're practically there! (followed by ducking his head under the table so he can laugh in secret)

The "secret silent laugh" gets a LOT of use at our house...