the dog has an onion

The dog has found an onion from somewhere.
He's walking around with it in his mouth, refusing to give it up.
His eyes are watering and he keeps coughing, but he keeps his distance from me with his oniony treasure.

I've asked him about the onion and why it's so important to him, but he is not forthcoming with his allium based plans.

I hope he's not building an onion gun.